thodg/libgit2

diff --git a/examples/diff.c b/examples/diff.c
index a465182..b81a868 100644
--- a/examples/diff.c
+++ b/examples/diff.c
@@ -133,7 +133,7 @@ int main(int argc, char *argv[])
 {
 	git_repository *repo = NULL;
 	git_tree *t1 = NULL, *t2 = NULL;
-	git_diff_options opts;
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	git_diff_list *diff;
 	int i, color = -1, compact = 0, cached = 0;
 	char *a, *dir = ".", *treeish1 = NULL, *treeish2 = NULL;
diff --git a/examples/network/clone.c b/examples/network/clone.c
index a718f30..7596523 100644
--- a/examples/network/clone.c
+++ b/examples/network/clone.c
@@ -51,7 +51,7 @@ int do_clone(git_repository *repo, int argc, char **argv)
 {
 	progress_data pd;
 	git_repository *cloned_repo = NULL;
-	git_checkout_opts checkout_opts;
+	git_checkout_opts checkout_opts = GIT_CHECKOUT_OPTS_INIT;
 	const char *url = argv[1];
 	const char *path = argv[2];
 	int error;
diff --git a/examples/network/fetch.c b/examples/network/fetch.c
index e341d2d..8048fd6 100644
--- a/examples/network/fetch.c
+++ b/examples/network/fetch.c
@@ -70,7 +70,7 @@ int fetch(git_repository *repo, int argc, char **argv)
 	const git_transfer_progress *stats;
 	pthread_t worker;
 	struct dl_data data;
-	git_remote_callbacks callbacks;
+	git_remote_callbacks callbacks = GIT_REMOTE_CALLBACKS_INIT;
 
 	argc = argc;
 	// Figure out whether it's a named remote or a URL
@@ -81,7 +81,6 @@ int fetch(git_repository *repo, int argc, char **argv)
 	}
 
 	// Set up the callbacks (only update_tips for now)
-	memset(&callbacks, 0, sizeof(callbacks));
 	callbacks.update_tips = &update_cb;
 	callbacks.progress = &progress_cb;
 	git_remote_set_callbacks(remote, &callbacks);
diff --git a/include/git2/checkout.h b/include/git2/checkout.h
index bd988db..ea6e219 100644
--- a/include/git2/checkout.h
+++ b/include/git2/checkout.h
@@ -186,7 +186,8 @@ typedef struct git_checkout_opts {
 	git_strarray paths;
 } git_checkout_opts;
 
-#define GIT_CHECKOUT_OPTS_INIT {1, 0}
+#define GIT_CHECKOUT_OPTS_VERSION 1
+#define GIT_CHECKOUT_OPTS_INIT {GIT_CHECKOUT_OPTS_VERSION, 0}
 
 /**
  * Updates files in the index and the working tree to match the content of the
diff --git a/include/git2/config.h b/include/git2/config.h
index af4d540..4855bab 100644
--- a/include/git2/config.h
+++ b/include/git2/config.h
@@ -49,6 +49,7 @@ typedef int  (*git_config_foreach_cb)(const git_config_entry *, void *);
  * access a configuration file
  */
 struct git_config_backend {
+	unsigned int version;
 	struct git_config *cfg;
 
 	/* Open means open the file/database and parse if necessary */
@@ -62,6 +63,8 @@ struct git_config_backend {
 	int (*refresh)(struct git_config_backend *);
 	void (*free)(struct git_config_backend *);
 };
+#define GIT_CONFIG_BACKEND_VERSION 1
+#define GIT_CONFIG_BACKEND_INIT {GIT_CONFIG_BACKEND_VERSION, 0}
 
 typedef enum {
 	GIT_CVAR_FALSE = 0,
diff --git a/include/git2/diff.h b/include/git2/diff.h
index fd00378..6732c30 100644
--- a/include/git2/diff.h
+++ b/include/git2/diff.h
@@ -106,16 +106,19 @@ typedef enum {
  * - max_size: maximum blob size to diff, above this treated as binary
  */
 typedef struct {
-	unsigned int version;		/**< version for the struct */
-	uint32_t flags;				/**< defaults to GIT_DIFF_NORMAL */
-	uint16_t context_lines;		/**< defaults to 3 */
-	uint16_t interhunk_lines;	/**< defaults to 0 */
-	char *old_prefix;			/**< defaults to "a" */
-	char *new_prefix;			/**< defaults to "b" */
-	git_strarray pathspec;		/**< defaults to show all paths */
-	git_off_t max_size;			/**< defaults to 512Mb */
+	unsigned int version;      /**< version for the struct */
+	uint32_t flags;            /**< defaults to GIT_DIFF_NORMAL */
+	uint16_t context_lines;    /**< defaults to 3 */
+	uint16_t interhunk_lines;  /**< defaults to 0 */
+	char *old_prefix;          /**< defaults to "a" */
+	char *new_prefix;          /**< defaults to "b" */
+	git_strarray pathspec;     /**< defaults to show all paths */
+	git_off_t max_size;        /**< defaults to 512mb */
 } git_diff_options;
 
+#define GIT_DIFF_OPTIONS_VERSION 1
+#define GIT_DIFF_OPTIONS_INIT {GIT_DIFF_OPTIONS_VERSION, 0}
+
 /**
  * The diff list object that contains all individual file deltas.
  */
@@ -304,6 +307,8 @@ typedef struct {
 	unsigned int target_limit;
 } git_diff_find_options;
 
+#define GIT_DIFF_FIND_OPTIONS_VERSION 1
+#define GIT_DIFF_FIND_OPTIONS_INIT {GIT_DIFF_FIND_OPTIONS_VERSION, 0}
 
 /** @name Diff List Generator Functions
  *
diff --git a/include/git2/odb_backend.h b/include/git2/odb_backend.h
index 04658f9..3963ae5 100644
--- a/include/git2/odb_backend.h
+++ b/include/git2/odb_backend.h
@@ -33,6 +33,7 @@ typedef int (*git_odb_foreach_cb)(const git_oid *id, void *payload);
  * An instance for a custom backend
  */
 struct git_odb_backend {
+	unsigned int version;
 	git_odb *odb;
 
 	/* read and read_prefix each return to libgit2 a buffer which
@@ -98,6 +99,9 @@ struct git_odb_backend {
 	void (* free)(struct git_odb_backend *);
 };
 
+#define GIT_ODB_BACKEND_VERSION 1
+#define GIT_ODB_BACKEND_INIT {GIT_ODB_BACKEND_VERSION, 0}
+
 /** Streaming mode */
 enum {
 	GIT_STREAM_RDONLY = (1 << 1),
diff --git a/include/git2/refs.h b/include/git2/refs.h
index f308210..cfc96a6 100644
--- a/include/git2/refs.h
+++ b/include/git2/refs.h
@@ -387,7 +387,7 @@ GIT_EXTERN(int) git_reference_foreach_glob(
 	git_repository *repo,
 	const char *glob,
 	unsigned int list_flags,
-	int (*callback)(const char *reference_name, void *payload),
+	git_reference_foreach_cb callback,
 	void *payload);
 
 /**
diff --git a/include/git2/remote.h b/include/git2/remote.h
index 0483cfc..75e2a59 100644
--- a/include/git2/remote.h
+++ b/include/git2/remote.h
@@ -347,12 +347,16 @@ typedef enum git_remote_completion_type {
  * Set the calbacks to be called by the remote.
  */
 struct git_remote_callbacks {
+	unsigned int version;
 	void (*progress)(const char *str, int len, void *data);
 	int (*completion)(git_remote_completion_type type, void *data);
 	int (*update_tips)(const char *refname, const git_oid *a, const git_oid *b, void *data);
 	void *payload;
 };
 
+#define GIT_REMOTE_CALLBACKS_VERSION 1
+#define GIT_REMOTE_CALLBACKS_INIT {GIT_REMOTE_CALLBACKS_VERSION, 0}
+
 /**
  * Set the callbacks for a remote
  *
@@ -361,8 +365,9 @@ struct git_remote_callbacks {
  *
  * @param remote the remote to configure
  * @param callbacks a pointer to the user's callback settings
+ * @return 0 or an error code
  */
-GIT_EXTERN(void) git_remote_set_callbacks(git_remote *remote, git_remote_callbacks *callbacks);
+GIT_EXTERN(int) git_remote_set_callbacks(git_remote *remote, git_remote_callbacks *callbacks);
 
 /**
  * Get the statistics structure that is filled in by the fetch operation.
diff --git a/include/git2/repository.h b/include/git2/repository.h
index e91108a..0d82b98 100644
--- a/include/git2/repository.h
+++ b/include/git2/repository.h
@@ -239,6 +239,7 @@ typedef enum {
  *        will be added pointing to this URL.
  */
 typedef struct {
+	unsigned int version;
 	uint32_t    flags;
 	uint32_t    mode;
 	const char *workdir_path;
@@ -248,6 +249,9 @@ typedef struct {
 	const char *origin_url;
 } git_repository_init_options;
 
+#define GIT_REPOSITORY_INIT_OPTIONS_VERSION 1
+#define GIT_REPOSITORY_INIT_OPTIONS_INIT {GIT_REPOSITORY_INIT_OPTIONS_VERSION, 0}
+
 /**
  * Create a new Git repository in the given folder with extended controls.
  *
diff --git a/include/git2/status.h b/include/git2/status.h
index c6926f3..1211f1d 100644
--- a/include/git2/status.h
+++ b/include/git2/status.h
@@ -164,6 +164,9 @@ typedef struct {
 	git_strarray      pathspec;
 } git_status_options;
 
+#define GIT_STATUS_OPTIONS_VERSION 1
+#define GIT_STATUS_OPTIONS_INIT {GIT_STATUS_OPTIONS_VERSION, 0}
+
 /**
  * Gather file status information and run callbacks as requested.
  *
diff --git a/include/git2/strarray.h b/include/git2/strarray.h
index 0305679..338d138 100644
--- a/include/git2/strarray.h
+++ b/include/git2/strarray.h
@@ -19,11 +19,10 @@
 GIT_BEGIN_DECL
 
 /** Array of strings */
-typedef struct _git_strarray git_strarray;
-struct _git_strarray {
+typedef struct git_strarray {
     char **strings;
     size_t count;
-};
+} git_strarray;
 
 /**
  * Close a string array object
diff --git a/include/git2/transport.h b/include/git2/transport.h
index 6172692..60ac3f2 100644
--- a/include/git2/transport.h
+++ b/include/git2/transport.h
@@ -82,6 +82,7 @@ typedef enum {
 typedef void (*git_transport_message_cb)(const char *str, int len, void *data);
 
 typedef struct git_transport {
+	unsigned int version;
 	/* Set progress and error callbacks */
 	int (*set_callbacks)(struct git_transport *transport,
 		git_transport_message_cb progress_cb,
@@ -140,6 +141,9 @@ typedef struct git_transport {
 	void (*free)(struct git_transport *transport);
 } git_transport;
 
+#define GIT_TRANSPORT_VERSION 1
+#define GIT_TRANSPORT_INIT {GIT_TRANSPORT_VERSION, 0}
+
 /**
  * Function to use to create a transport from a URL. The transport database
  * is scanned to find a transport that implements the scheme of the URI (i.e.
@@ -284,6 +288,7 @@ typedef int (*git_smart_subtransport_cb)(
 typedef struct git_smart_subtransport_definition {
 	/* The function to use to create the git_smart_subtransport */
 	git_smart_subtransport_cb callback;
+
 	/* True if the protocol is stateless; false otherwise. For example,
 	 * http:// is stateless, but git:// is not. */
 	unsigned rpc : 1;
diff --git a/src/checkout.c b/src/checkout.c
index 8e5de0a..33de7ad 100644
--- a/src/checkout.c
+++ b/src/checkout.c
@@ -232,7 +232,7 @@ static void normalize_options(
 	assert(normalized);
 
 	if (!proposed)
-		memset(normalized, 0, sizeof(git_checkout_opts));
+		GIT_INIT_STRUCTURE(normalized, GIT_CHECKOUT_OPTS_VERSION);
 	else
 		memmove(normalized, proposed, sizeof(git_checkout_opts));
 
@@ -611,7 +611,7 @@ int git_checkout_index(
 	git_checkout_opts *opts)
 {
 	git_diff_list *diff = NULL;
-	git_diff_options diff_opts = {0};
+	git_diff_options diff_opts = GIT_DIFF_OPTIONS_INIT;
 	git_checkout_opts checkout_opts;
 	checkout_diff_data data;
 	git_buf workdir = GIT_BUF_INIT;
@@ -621,6 +621,8 @@ int git_checkout_index(
 
 	assert(repo);
 
+	GITERR_CHECK_VERSION(opts, GIT_CHECKOUT_OPTS_VERSION, "git_checkout_opts");
+
 	if ((error = git_repository__ensure_not_bare(repo, "checkout")) < 0)
 		return error;
 
diff --git a/src/common.h b/src/common.h
index b3b5515..3152669 100644
--- a/src/common.h
+++ b/src/common.h
@@ -65,6 +65,33 @@ void giterr_set(int error_class, const char *string, ...);
  */
 int giterr_set_regex(const regex_t *regex, int error_code);
 
+/**
+ * Check a versioned structure for validity
+ */
+GIT_INLINE(bool) giterr__check_version(const void *structure, unsigned int expected_max, const char *name)
+{
+	if (!structure)
+		return true;
+
+	unsigned int actual = *(const unsigned int*)structure;
+	if (actual > 0 && actual <= expected_max)
+		return true;
+
+	giterr_set(GITERR_INVALID, "Invalid version %d on %s", actual, name);
+	return false;
+}
+#define GITERR_CHECK_VERSION(S,V,N) if (!giterr__check_version(S,V,N)) return -1
+
+/**
+ * Initialize a structure with a version.
+ */
+GIT_INLINE(void) git__init_structure(void *structure, size_t len, unsigned int version)
+{
+	memset(structure, 0, len);
+	*((int*)structure) = version;
+}
+#define GIT_INIT_STRUCTURE(S,V) git__init_structure(S, sizeof(*S), V)
+
 /* NOTE: other giterr functions are in the public errors.h header file */
 
 #include "util.h"
diff --git a/src/config.c b/src/config.c
index 6347f7d..d422447 100644
--- a/src/config.c
+++ b/src/config.c
@@ -259,6 +259,8 @@ int git_config_add_backend(
 
 	assert(cfg && file);
 
+	GITERR_CHECK_VERSION(file, GIT_CONFIG_BACKEND_VERSION, "git_config_backend");
+
 	if ((result = file->open(file, level)) < 0)
 		return result;
 
diff --git a/src/config_file.c b/src/config_file.c
index 354a919..6e29832 100644
--- a/src/config_file.c
+++ b/src/config_file.c
@@ -545,10 +545,10 @@ int git_config_file__ondisk(git_config_backend **out, const char *path)
 {
 	diskfile_backend *backend;
 
-	backend = git__malloc(sizeof(diskfile_backend));
+	backend = git__calloc(1, sizeof(diskfile_backend));
 	GITERR_CHECK_ALLOC(backend);
 
-	memset(backend, 0x0, sizeof(diskfile_backend));
+	backend->parent.version = GIT_CONFIG_BACKEND_VERSION;
 
 	backend->file_path = git__strdup(path);
 	GITERR_CHECK_ALLOC(backend->file_path);
diff --git a/src/diff.c b/src/diff.c
index 86f76f9..46d96bb 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -755,14 +755,14 @@ fail:
 	return error;
 }
 
-
 #define DIFF_FROM_ITERATORS(MAKE_FIRST, MAKE_SECOND) do { \
 	git_iterator *a = NULL, *b = NULL; \
 	char *pfx = opts ? git_pathspec_prefix(&opts->pathspec) : NULL; \
-    if (!(error = MAKE_FIRST) && !(error = MAKE_SECOND)) \
+	GITERR_CHECK_VERSION(opts, GIT_DIFF_OPTIONS_VERSION, "git_diff_options"); \
+	if (!(error = MAKE_FIRST) && !(error = MAKE_SECOND)) \
 		error = diff_from_iterators(diff, repo, a, b, opts); \
 	git__free(pfx); git_iterator_free(a); git_iterator_free(b); \
-    } while (0)
+} while (0)
 
 int git_diff_tree_to_tree(
 	git_diff_list **diff,
diff --git a/src/diff.h b/src/diff.h
index 1e3be75..f93bab1 100644
--- a/src/diff.h
+++ b/src/diff.h
@@ -61,5 +61,6 @@ extern bool git_diff_delta__should_skip(
 extern int git_diff__oid_for_file(
 	git_repository *, const char *, uint16_t, git_off_t, git_oid *);
 
+
 #endif
 
diff --git a/src/diff_output.c b/src/diff_output.c
index e137fd0..b18255d 100644
--- a/src/diff_output.c
+++ b/src/diff_output.c
@@ -1266,6 +1266,8 @@ int git_diff_blobs(
 	git_diff_delta delta;
 	git_diff_patch patch;
 
+	GITERR_CHECK_VERSION(options, GIT_DIFF_OPTIONS_VERSION, "git_diff_options");
+
 	if (options && (options->flags & GIT_DIFF_REVERSE)) {
 		git_blob *swap = old_blob;
 		old_blob = new_blob;
diff --git a/src/diff_tform.c b/src/diff_tform.c
index 987d4b8..0c58859 100644
--- a/src/diff_tform.c
+++ b/src/diff_tform.c
@@ -187,7 +187,8 @@ static int normalize_find_opts(
 	if (given != NULL)
 		memcpy(opts, given, sizeof(*opts));
 	else {
-		memset(opts, 0, sizeof(*opts));
+		git_diff_find_options init = GIT_DIFF_FIND_OPTIONS_INIT;
+		memmove(opts, &init, sizeof(init));
 
 		opts->flags = GIT_DIFF_FIND_RENAMES;
 
@@ -198,6 +199,8 @@ static int normalize_find_opts(
 			opts->flags = GIT_DIFF_FIND_RENAMES | GIT_DIFF_FIND_COPIES;
 	}
 
+	GITERR_CHECK_VERSION(opts, GIT_DIFF_FIND_OPTIONS_VERSION, "git_diff_find_options");
+
 	/* some flags imply others */
 
 	if (opts->flags & GIT_DIFF_FIND_RENAMES_FROM_REWRITES)
diff --git a/src/notes.c b/src/notes.c
index dd36cc2..f96b5b1 100644
--- a/src/notes.c
+++ b/src/notes.c
@@ -11,6 +11,7 @@
 #include "refs.h"
 #include "config.h"
 #include "iterator.h"
+#include "signature.h"
 
 static int find_subtree_in_current_level(
 	git_tree **out,
diff --git a/src/odb.c b/src/odb.c
index 63b6828..b6d1f79 100644
--- a/src/odb.c
+++ b/src/odb.c
@@ -369,6 +369,8 @@ static int add_backend_internal(git_odb *odb, git_odb_backend *backend, int prio
 
 	assert(odb && backend);
 
+	GITERR_CHECK_VERSION(backend, GIT_ODB_BACKEND_VERSION, "git_odb_backend");
+
 	/* Check if the backend is already owned by another ODB */
 	assert(!backend->odb || backend->odb == odb);
 
diff --git a/src/odb_loose.c b/src/odb_loose.c
index e2f1aec..df86d90 100644
--- a/src/odb_loose.c
+++ b/src/odb_loose.c
@@ -915,6 +915,7 @@ int git_odb_backend_loose(
 	backend = git__calloc(1, sizeof(loose_backend));
 	GITERR_CHECK_ALLOC(backend);
 
+	backend->parent.version = GIT_ODB_BACKEND_VERSION;
 	backend->objects_dir = git__strdup(objects_dir);
 	GITERR_CHECK_ALLOC(backend->objects_dir);
 
diff --git a/src/odb_pack.c b/src/odb_pack.c
index fc282dd..b1a46c9 100644
--- a/src/odb_pack.c
+++ b/src/odb_pack.c
@@ -569,6 +569,7 @@ int git_odb_backend_one_pack(git_odb_backend **backend_out, const char *idx)
 
 	backend = git__calloc(1, sizeof(struct pack_backend));
 	GITERR_CHECK_ALLOC(backend);
+	backend->parent.version = GIT_ODB_BACKEND_VERSION;
 
 	if (git_vector_init(&backend->packs, 1, NULL) < 0)
 		goto on_error;
@@ -601,6 +602,7 @@ int git_odb_backend_pack(git_odb_backend **backend_out, const char *objects_dir)
 
 	backend = git__calloc(1, sizeof(struct pack_backend));
 	GITERR_CHECK_ALLOC(backend);
+	backend->parent.version = GIT_ODB_BACKEND_VERSION;
 
 	if (git_vector_init(&backend->packs, 8, packfile_sort__cb) < 0 ||
 		git_buf_joinpath(&path, objects_dir, "pack") < 0)
diff --git a/src/remote.c b/src/remote.c
index dc8d968..5b75e51 100644
--- a/src/remote.c
+++ b/src/remote.c
@@ -1000,10 +1000,12 @@ void git_remote_check_cert(git_remote *remote, int check)
 	remote->check_cert = check;
 }
 
-void git_remote_set_callbacks(git_remote *remote, git_remote_callbacks *callbacks)
+int git_remote_set_callbacks(git_remote *remote, git_remote_callbacks *callbacks)
 {
 	assert(remote && callbacks);
 
+	GITERR_CHECK_VERSION(callbacks, GIT_REMOTE_CALLBACKS_VERSION, "git_remote_callbacks");
+
 	memcpy(&remote->callbacks, callbacks, sizeof(git_remote_callbacks));
 
 	if (remote->transport && remote->transport->set_callbacks)
@@ -1011,6 +1013,8 @@ void git_remote_set_callbacks(git_remote *remote, git_remote_callbacks *callback
 			remote->callbacks.progress,
 			NULL,
 			remote->callbacks.payload);
+
+	return 0;
 }
 
 void git_remote_set_cred_acquire_cb(
@@ -1026,6 +1030,8 @@ int git_remote_set_transport(git_remote *remote, git_transport *transport)
 {
 	assert(remote && transport);
 
+	GITERR_CHECK_VERSION(transport, GIT_TRANSPORT_VERSION, "git_transport");
+
 	if (remote->transport) {
 		giterr_set(GITERR_NET, "A transport is already bound to this remote");
 		return -1;
diff --git a/src/repository.c b/src/repository.c
index b49b49b..10ed12b 100644
--- a/src/repository.c
+++ b/src/repository.c
@@ -1151,9 +1151,8 @@ static int repo_init_create_origin(git_repository *repo, const char *url)
 int git_repository_init(
 	git_repository **repo_out, const char *path, unsigned is_bare)
 {
-	git_repository_init_options opts;
+	git_repository_init_options opts = GIT_REPOSITORY_INIT_OPTIONS_INIT;
 
-	memset(&opts, 0, sizeof(opts));
 	opts.flags = GIT_REPOSITORY_INIT_MKPATH; /* don't love this default */
 	if (is_bare)
 		opts.flags |= GIT_REPOSITORY_INIT_BARE;
@@ -1171,6 +1170,8 @@ int git_repository_init_ext(
 
 	assert(out && given_repo && opts);
 
+	GITERR_CHECK_VERSION(opts, GIT_REPOSITORY_INIT_OPTIONS_VERSION, "git_repository_init_options");
+
 	error = repo_init_directories(&repo_path, &wd_path, given_repo, opts);
 	if (error < 0)
 		goto cleanup;
diff --git a/src/reset.c b/src/reset.c
index d410a88..17b4b90 100644
--- a/src/reset.c
+++ b/src/reset.c
@@ -69,7 +69,7 @@ int git_reset(
 	git_index *index = NULL;
 	git_tree *tree = NULL;
 	int error = -1;
-	git_checkout_opts opts;
+	git_checkout_opts opts = GIT_CHECKOUT_OPTS_INIT;
 
 	assert(repo && target);
 	assert(reset_type == GIT_RESET_SOFT
@@ -136,7 +136,6 @@ int git_reset(
 		goto cleanup;
 	}
 
-	memset(&opts, 0, sizeof(opts));
 	opts.checkout_strategy = GIT_CHECKOUT_FORCE;
 
 	if (git_checkout_index(repo, NULL, &opts) < 0) {
diff --git a/src/signature.c b/src/signature.c
index 0159488..7d043e6 100644
--- a/src/signature.c
+++ b/src/signature.c
@@ -264,7 +264,7 @@ int git_signature__parse(git_signature *sig, const char **buffer_out,
 	const char *line_end, *name_end, *email_end, *tz_start, *time_start;
 	int error = 0;
 
-	memset(sig, 0x0, sizeof(git_signature));
+	memset(sig, 0, sizeof(git_signature));
 
 	if ((line_end = memchr(buffer, ender, buffer_end - buffer)) == NULL)
 		return signature_error("no newline given");
diff --git a/src/stash.c b/src/stash.c
index 107cbe3..e32d8fa 100644
--- a/src/stash.c
+++ b/src/stash.c
@@ -14,6 +14,7 @@
 #include "git2/stash.h"
 #include "git2/status.h"
 #include "git2/checkout.h"
+#include "signature.h"
 
 static int create_error(int error, const char *msg)
 {
@@ -229,7 +230,7 @@ static int build_untracked_tree(
 {
 	git_tree *i_tree = NULL;
 	git_diff_list *diff = NULL;
-	git_diff_options opts = {0};
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	struct cb_data data = {0};
 	int error = -1;
 
@@ -315,7 +316,7 @@ static int build_workdir_tree(
 	git_repository *repo = git_index_owner(index);
 	git_tree *b_tree = NULL;
 	git_diff_list *diff = NULL, *diff2 = NULL;
-	git_diff_options opts = {0};
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	struct cb_data data = {0};
 	int error = -1;
 
@@ -471,9 +472,8 @@ static int ensure_there_are_changes_to_stash(
 	bool include_ignored_files)
 {
 	int error;
-	git_status_options opts;
+	git_status_options opts = GIT_STATUS_OPTIONS_INIT;
 
-	memset(&opts, 0, sizeof(opts));
 	opts.show  = GIT_STATUS_SHOW_INDEX_AND_WORKDIR;
 	if (include_untracked_files)
 		opts.flags = GIT_STATUS_OPT_INCLUDE_UNTRACKED |
@@ -498,9 +498,7 @@ static int reset_index_and_workdir(
 	git_commit *commit,
 	bool remove_untracked)
 {
-	git_checkout_opts opts;
-
-	memset(&opts, 0, sizeof(git_checkout_opts));
+	git_checkout_opts opts = GIT_CHECKOUT_OPTS_INIT;
 
 	opts.checkout_strategy =
 		GIT_CHECKOUT_UPDATE_MODIFIED | GIT_CHECKOUT_UPDATE_UNTRACKED;
diff --git a/src/status.c b/src/status.c
index c7dea2c..1ad835a 100644
--- a/src/status.c
+++ b/src/status.c
@@ -108,7 +108,7 @@ int git_status_foreach_ext(
 	void *payload)
 {
 	int err = 0;
-	git_diff_options diffopt;
+	git_diff_options diffopt = GIT_DIFF_OPTIONS_INIT;
 	git_diff_list *idx2head = NULL, *wd2idx = NULL;
 	git_tree *head = NULL;
 	git_status_show_t show =
@@ -117,6 +117,8 @@ int git_status_foreach_ext(
 
 	assert(show <= GIT_STATUS_SHOW_INDEX_THEN_WORKDIR);
 
+	GITERR_CHECK_VERSION(opts, GIT_STATUS_OPTIONS_VERSION, "git_status_options");
+
 	if (show != GIT_STATUS_SHOW_INDEX_ONLY &&
 		(err = git_repository__ensure_not_bare(repo, "status")) < 0)
 		return err;
@@ -126,7 +128,6 @@ int git_status_foreach_ext(
 		!(err == GIT_ENOTFOUND || err == GIT_EORPHANEDHEAD))
 			return err;
 
-	memset(&diffopt, 0, sizeof(diffopt));
 	memcpy(&diffopt.pathspec, &opts->pathspec, sizeof(diffopt.pathspec));
 
 	diffopt.flags = GIT_DIFF_INCLUDE_TYPECHANGE;
@@ -181,9 +182,8 @@ int git_status_foreach(
 	git_status_cb callback,
 	void *payload)
 {
-	git_status_options opts;
+	git_status_options opts = GIT_STATUS_OPTIONS_INIT;
 
-	memset(&opts, 0, sizeof(opts));
 	opts.show  = GIT_STATUS_SHOW_INDEX_AND_WORKDIR;
 	opts.flags = GIT_STATUS_OPT_INCLUDE_IGNORED |
 		GIT_STATUS_OPT_INCLUDE_UNTRACKED |
@@ -224,16 +224,14 @@ int git_status_file(
 	const char *path)
 {
 	int error;
-	git_status_options opts;
-	struct status_file_info sfi;
+	git_status_options opts = GIT_STATUS_OPTIONS_INIT;
+	struct status_file_info sfi = {0};
 
 	assert(status_flags && repo && path);
 
-	memset(&sfi, 0, sizeof(sfi));
 	if ((sfi.expected = git__strdup(path)) == NULL)
 		return -1;
 
-	memset(&opts, 0, sizeof(opts));
 	opts.show  = GIT_STATUS_SHOW_INDEX_AND_WORKDIR;
 	opts.flags = GIT_STATUS_OPT_INCLUDE_IGNORED |
 		GIT_STATUS_OPT_INCLUDE_UNTRACKED |
diff --git a/src/submodule.c b/src/submodule.c
index c117255..21a1875 100644
--- a/src/submodule.c
+++ b/src/submodule.c
@@ -205,7 +205,7 @@ int git_submodule_add_setup(
 	git_config_backend *mods = NULL;
 	git_submodule *sm;
 	git_buf name = GIT_BUF_INIT, real_url = GIT_BUF_INIT;
-	git_repository_init_options initopt;
+	git_repository_init_options initopt = GIT_REPOSITORY_INIT_OPTIONS_INIT;
 	git_repository *subrepo = NULL;
 
 	assert(repo && url && path);
@@ -275,7 +275,6 @@ int git_submodule_add_setup(
 	 * Old style: sub-repo goes directly into repo/<name>/.git/
 	 */
 
-	memset(&initopt, 0, sizeof(initopt));
 	initopt.flags = GIT_REPOSITORY_INIT_MKPATH |
 		GIT_REPOSITORY_INIT_NO_REINIT;
 	initopt.origin_url = real_url.ptr;
@@ -1439,7 +1438,7 @@ static int submodule_wd_status(unsigned int *status, git_submodule *sm)
 
 	if (sm_repo != NULL) {
 		git_tree *sm_head;
-		git_diff_options opt;
+		git_diff_options opt = GIT_DIFF_OPTIONS_INIT;
 		git_diff_list *diff;
 
 		/* the diffs below could be optimized with an early termination
@@ -1452,7 +1451,6 @@ static int submodule_wd_status(unsigned int *status, git_submodule *sm)
 		if ((error = git_repository_head_tree(&sm_head, sm_repo)) < 0)
 			return error;
 
-		memset(&opt, 0, sizeof(opt));
 		if (sm->ignore == GIT_SUBMODULE_IGNORE_NONE)
 			opt.flags |= GIT_DIFF_INCLUDE_UNTRACKED;
 
diff --git a/src/transports/local.c b/src/transports/local.c
index 62e8024..768daf3 100644
--- a/src/transports/local.c
+++ b/src/transports/local.c
@@ -403,11 +403,10 @@ int git_transport_local(git_transport **out, git_remote *owner, void *param)
 
 	GIT_UNUSED(param);
 
-	t = git__malloc(sizeof(transport_local));
+	t = git__calloc(1, sizeof(transport_local));
 	GITERR_CHECK_ALLOC(t);
 
-	memset(t, 0x0, sizeof(transport_local));
-		
+	t->parent.version = GIT_TRANSPORT_VERSION;
 	t->parent.connect = local_connect;
 	t->parent.negotiate_fetch = local_negotiate_fetch;
 	t->parent.download_pack = local_download_pack;
diff --git a/src/transports/smart.c b/src/transports/smart.c
index 94d389b..5300a47 100644
--- a/src/transports/smart.c
+++ b/src/transports/smart.c
@@ -303,6 +303,7 @@ int git_transport_smart(git_transport **out, git_remote *owner, void *param)
 	t = git__calloc(sizeof(transport_smart), 1);
 	GITERR_CHECK_ALLOC(t);
 
+	t->parent.version = GIT_TRANSPORT_VERSION;
 	t->parent.set_callbacks = git_smart__set_callbacks;
 	t->parent.connect = git_smart__connect;
 	t->parent.close = git_smart__close;
diff --git a/tests-clar/checkout/index.c b/tests-clar/checkout/index.c
index b6d6372..a67765b 100644
--- a/tests-clar/checkout/index.c
+++ b/tests-clar/checkout/index.c
@@ -25,7 +25,7 @@ void test_checkout_index__initialize(void)
 {
 	git_tree *tree;
 
-	memset(&g_opts, 0, sizeof(g_opts));
+	GIT_INIT_STRUCTURE(&g_opts, GIT_CHECKOUT_OPTS_VERSION);
 	g_opts.checkout_strategy = GIT_CHECKOUT_SAFE;
 
 	g_repo = cl_git_sandbox_init("testrepo");
@@ -66,7 +66,7 @@ void test_checkout_index__cannot_checkout_a_bare_repository(void)
 {
 	test_checkout_index__cleanup();
 
-	memset(&g_opts, 0, sizeof(g_opts));
+	GIT_INIT_STRUCTURE(&g_opts, GIT_CHECKOUT_OPTS_VERSION);
 	g_repo = cl_git_sandbox_init("testrepo.git");
 
 	cl_git_fail(git_checkout_index(g_repo, NULL, NULL));
@@ -426,3 +426,21 @@ void test_checkout_index__can_overcome_name_clashes(void)
 
 	git_index_free(index);
 }
+
+void test_checkout_index__validates_struct_version(void)
+{
+	const git_error *err;
+
+	g_opts.version = 1024;
+	cl_git_fail(git_checkout_index(g_repo, NULL, &g_opts));
+
+	err = giterr_last();
+	cl_assert_equal_i(err->klass, GITERR_INVALID);
+
+	g_opts.version = 0;
+	giterr_clear();
+	cl_git_fail(git_checkout_index(g_repo, NULL, &g_opts));
+
+	err = giterr_last();
+	cl_assert_equal_i(err->klass, GITERR_INVALID);
+}
diff --git a/tests-clar/checkout/tree.c b/tests-clar/checkout/tree.c
index 534c460..88dbe4f 100644
--- a/tests-clar/checkout/tree.c
+++ b/tests-clar/checkout/tree.c
@@ -11,7 +11,7 @@ void test_checkout_tree__initialize(void)
 {
 	g_repo = cl_git_sandbox_init("testrepo");
 
-	memset(&g_opts, 0, sizeof(g_opts));
+	GIT_INIT_STRUCTURE(&g_opts, GIT_CHECKOUT_OPTS_VERSION);
 	g_opts.checkout_strategy = GIT_CHECKOUT_SAFE;
 }
 
diff --git a/tests-clar/checkout/typechange.c b/tests-clar/checkout/typechange.c
index cd34885..98c15bc 100644
--- a/tests-clar/checkout/typechange.c
+++ b/tests-clar/checkout/typechange.c
@@ -38,7 +38,7 @@ void test_checkout_typechange__checkout_typechanges(void)
 {
 	int i;
 	git_object *obj;
-	git_checkout_opts opts = {0};
+	git_checkout_opts opts = GIT_CHECKOUT_OPTS_INIT;
 
 	opts.checkout_strategy = GIT_CHECKOUT_FORCE;
 
diff --git a/tests-clar/commit/parse.c b/tests-clar/commit/parse.c
index bbb502c..8075f26 100644
--- a/tests-clar/commit/parse.c
+++ b/tests-clar/commit/parse.c
@@ -149,7 +149,7 @@ void test_commit_parse__signature(void)
    {
       const char *str = passcase->string;
       size_t len = strlen(passcase->string);
-      struct git_signature person = {NULL, NULL, {0, 0}};
+      struct git_signature person = {0};
       cl_git_pass(git_signature__parse(&person, &str, str + len, passcase->header, '\n'));
       cl_assert(strcmp(passcase->name, person.name) == 0);
       cl_assert(strcmp(passcase->email, person.email) == 0);
@@ -162,7 +162,7 @@ void test_commit_parse__signature(void)
    {
       const char *str = failcase->string;
       size_t len = strlen(failcase->string);
-      git_signature person = {NULL, NULL, {0, 0}};
+      git_signature person = {0};
       cl_git_fail(git_signature__parse(&person, &str, str + len, failcase->header, '\n'));
       git__free(person.name); git__free(person.email);
    }
diff --git a/tests-clar/config/backend.c b/tests-clar/config/backend.c
new file mode 100644
index 0000000..1cf7702
--- /dev/null
+++ b/tests-clar/config/backend.c
@@ -0,0 +1,20 @@
+#include "clar_libgit2.h"
+
+void test_config_backend__checks_version(void)
+{
+	git_config *cfg;
+	git_config_backend backend = GIT_CONFIG_BACKEND_INIT;
+	backend.version = 1024;
+	const git_error *err;
+
+	cl_git_pass(git_config_new(&cfg));
+	cl_git_fail(git_config_add_backend(cfg, &backend, 0, false));
+	err = giterr_last();
+	cl_assert_equal_i(GITERR_INVALID, err->klass);
+
+	giterr_clear();
+	backend.version = 1024;
+	cl_git_fail(git_config_add_backend(cfg, &backend, 0, false));
+	err = giterr_last();
+	cl_assert_equal_i(GITERR_INVALID, err->klass);
+}
diff --git a/tests-clar/diff/blob.c b/tests-clar/diff/blob.c
index 6a5645d..d7fdba0 100644
--- a/tests-clar/diff/blob.c
+++ b/tests-clar/diff/blob.c
@@ -12,7 +12,7 @@ void test_diff_blob__initialize(void)
 
 	g_repo = cl_git_sandbox_init("attr");
 
-	memset(&opts, 0, sizeof(opts));
+	GIT_INIT_STRUCTURE(&opts, GIT_DIFF_OPTIONS_VERSION);
 	opts.context_lines = 1;
 	opts.interhunk_lines = 0;
 
@@ -313,3 +313,25 @@ void test_diff_blob__comparing_two_text_blobs_honors_interhunkcontext(void)
 
 	git_blob_free(old_d);
 }
+
+void test_diff_blob__checks_options_version_too_low(void)
+{
+	const git_error *err;
+
+	opts.version = 0;
+	cl_git_fail(git_diff_blobs(
+		d, alien, &opts, diff_file_cb, diff_hunk_cb, diff_line_cb, &expected));
+	err = giterr_last();
+	cl_assert_equal_i(GITERR_INVALID, err->klass);
+}
+
+void test_diff_blob__checks_options_version_too_high(void)
+{
+	const git_error *err;
+
+	opts.version = 1024;
+	cl_git_fail(git_diff_blobs(
+		d, alien, &opts, diff_file_cb, diff_hunk_cb, diff_line_cb, &expected));
+	err = giterr_last();
+	cl_assert_equal_i(GITERR_INVALID, err->klass);
+}
diff --git a/tests-clar/diff/diff_helpers.h b/tests-clar/diff/diff_helpers.h
index 12591f6..49c2652 100644
--- a/tests-clar/diff/diff_helpers.h
+++ b/tests-clar/diff/diff_helpers.h
@@ -48,3 +48,4 @@ extern int diff_foreach_via_iterator(
 	void *data);
 
 extern void diff_print(FILE *fp, git_diff_list *diff);
+
diff --git a/tests-clar/diff/diffiter.c b/tests-clar/diff/diffiter.c
index 133392c..306a13e 100644
--- a/tests-clar/diff/diffiter.c
+++ b/tests-clar/diff/diffiter.c
@@ -76,7 +76,7 @@ void test_diff_diffiter__iterate_files_2(void)
 void test_diff_diffiter__iterate_files_and_hunks(void)
 {
 	git_repository *repo = cl_git_sandbox_init("status");
-	git_diff_options opts = {0};
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	git_diff_list *diff = NULL;
 	size_t d, num_d;
 	int file_count = 0, hunk_count = 0;
@@ -129,7 +129,7 @@ void test_diff_diffiter__iterate_files_and_hunks(void)
 void test_diff_diffiter__max_size_threshold(void)
 {
 	git_repository *repo = cl_git_sandbox_init("status");
-	git_diff_options opts = {0};
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	git_diff_list *diff = NULL;
 	int file_count = 0, binary_count = 0, hunk_count = 0;
 	size_t d, num_d;
@@ -207,7 +207,7 @@ void test_diff_diffiter__max_size_threshold(void)
 void test_diff_diffiter__iterate_all(void)
 {
 	git_repository *repo = cl_git_sandbox_init("status");
-	git_diff_options opts = {0};
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	git_diff_list *diff = NULL;
 	diff_expects exp = {0};
 	size_t d, num_d;
@@ -280,7 +280,7 @@ static void iterate_over_patch(git_diff_patch *patch, diff_expects *exp)
 void test_diff_diffiter__iterate_randomly_while_saving_state(void)
 {
 	git_repository *repo = cl_git_sandbox_init("status");
-	git_diff_options opts = {0};
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	git_diff_list *diff = NULL;
 	diff_expects exp = {0};
 	git_diff_patch *patches[PATCH_CACHE];
@@ -441,3 +441,25 @@ void test_diff_diffiter__iterate_and_generate_patch_text(void)
 
 	git_diff_list_free(diff);
 }
+
+void test_diff_diffiter__checks_options_version(void)
+{
+	git_repository *repo = cl_git_sandbox_init("status");
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
+	git_diff_list *diff = NULL;
+	const git_error *err;
+
+	opts.version = 0;
+	opts.flags |= GIT_DIFF_INCLUDE_IGNORED | GIT_DIFF_INCLUDE_UNTRACKED;
+
+	cl_git_fail(git_diff_workdir_to_index(&diff, repo, NULL, &opts));
+	err = giterr_last();
+	cl_assert_equal_i(GITERR_INVALID, err->klass);
+
+	giterr_clear();
+	opts.version = 1024;
+	cl_git_fail(git_diff_workdir_to_index(&diff, repo, NULL, &opts));
+	err = giterr_last();
+	cl_assert_equal_i(GITERR_INVALID, err->klass);
+}
+
diff --git a/tests-clar/diff/index.c b/tests-clar/diff/index.c
index 9591e34..267b329 100644
--- a/tests-clar/diff/index.c
+++ b/tests-clar/diff/index.c
@@ -20,7 +20,7 @@ void test_diff_index__0(void)
 	const char *b_commit = "0017bd4ab1ec3"; /* the start */
 	git_tree *a = resolve_commit_oid_to_tree(g_repo, a_commit);
 	git_tree *b = resolve_commit_oid_to_tree(g_repo, b_commit);
-	git_diff_options opts = {0};
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	git_diff_list *diff = NULL;
 	diff_expects exp;
 
@@ -113,7 +113,7 @@ void test_diff_index__1(void)
 	const char *b_commit = "0017bd4ab1ec3"; /* the start */
 	git_tree *a = resolve_commit_oid_to_tree(g_repo, a_commit);
 	git_tree *b = resolve_commit_oid_to_tree(g_repo, b_commit);
-	git_diff_options opts = {0};
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	git_diff_list *diff = NULL;
 	diff_expects exp;
 
@@ -140,3 +140,24 @@ void test_diff_index__1(void)
 	git_tree_free(a);
 	git_tree_free(b);
 }
+
+void test_diff_index__checks_options_version(void)
+{
+	const char *a_commit = "26a125ee1bf";
+	git_tree *a = resolve_commit_oid_to_tree(g_repo, a_commit);
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
+	git_diff_list *diff;
+	const git_error *err;
+
+	opts.version = 0;
+	cl_git_fail(git_diff_index_to_tree(&diff, g_repo, a, NULL, &opts));
+	err = giterr_last();
+	cl_assert_equal_i(GITERR_INVALID, err->klass);
+
+	giterr_clear();
+	opts.version = 1024;
+	cl_git_fail(git_diff_index_to_tree(&diff, g_repo, a, NULL, &opts));
+	err = giterr_last();
+	cl_assert_equal_i(GITERR_INVALID, err->klass);
+}
+
diff --git a/tests-clar/diff/rename.c b/tests-clar/diff/rename.c
index 0d57f8f..2995b4e 100644
--- a/tests-clar/diff/rename.c
+++ b/tests-clar/diff/rename.c
@@ -33,8 +33,8 @@ void test_diff_rename__match_oid(void)
 	const char *new_sha = "2bc7f351d20b53f1c72c16c4b036e491c478c49a";
 	git_tree *old_tree, *new_tree;
 	git_diff_list *diff;
-	git_diff_options diffopts = {0};
-	git_diff_find_options opts;
+	git_diff_options diffopts = GIT_DIFF_OPTIONS_INIT;
+	git_diff_find_options opts = GIT_DIFF_FIND_OPTIONS_INIT;
 	diff_expects exp;
 
 	old_tree = resolve_commit_oid_to_tree(g_repo, old_sha);
@@ -43,7 +43,6 @@ void test_diff_rename__match_oid(void)
 	/* Must pass GIT_DIFF_INCLUDE_UNMODIFIED if you expect to emulate
 	 * --find-copies-harder during rename transformion...
 	 */
-	memset(&diffopts, 0, sizeof(diffopts));
 	diffopts.flags |= GIT_DIFF_INCLUDE_UNMODIFIED;
 
 	cl_git_pass(git_diff_tree_to_tree(
@@ -85,7 +84,6 @@ void test_diff_rename__match_oid(void)
 	 *          31e47d8c1fa36d7f8d537b96158e3f024de0a9f2 \
 	 *          2bc7f351d20b53f1c72c16c4b036e491c478c49a
 	 */
-	memset(&opts, 0, sizeof(opts));
 	opts.flags = GIT_DIFF_FIND_COPIES_FROM_UNMODIFIED;
 	cl_git_pass(git_diff_find_similar(diff, &opts));
 
@@ -103,3 +101,35 @@ void test_diff_rename__match_oid(void)
 	git_tree_free(old_tree);
 	git_tree_free(new_tree);
 }
+
+void test_diff_rename__checks_options_version(void)
+{
+	const char *old_sha = "31e47d8c1fa36d7f8d537b96158e3f024de0a9f2";
+	const char *new_sha = "2bc7f351d20b53f1c72c16c4b036e491c478c49a";
+	git_tree *old_tree, *new_tree;
+	git_diff_list *diff;
+	git_diff_options diffopts = GIT_DIFF_OPTIONS_INIT;
+	git_diff_find_options opts = GIT_DIFF_FIND_OPTIONS_INIT;
+	const git_error *err;
+
+	old_tree = resolve_commit_oid_to_tree(g_repo, old_sha);
+	new_tree = resolve_commit_oid_to_tree(g_repo, new_sha);
+	diffopts.flags |= GIT_DIFF_INCLUDE_UNMODIFIED;
+	cl_git_pass(git_diff_tree_to_tree(
+		&diff, g_repo, old_tree, new_tree, &diffopts));
+
+	opts.version = 0;
+	cl_git_fail(git_diff_find_similar(diff, &opts));
+	err = giterr_last();
+	cl_assert_equal_i(GITERR_INVALID, err->klass);
+
+	giterr_clear();
+	opts.version = 1024;
+	cl_git_fail(git_diff_find_similar(diff, &opts));
+	err = giterr_last();
+	cl_assert_equal_i(GITERR_INVALID, err->klass);
+
+	git_diff_list_free(diff);
+	git_tree_free(old_tree);
+	git_tree_free(new_tree);
+}
diff --git a/tests-clar/diff/tree.c b/tests-clar/diff/tree.c
index 58dc4e6..442e53b 100644
--- a/tests-clar/diff/tree.c
+++ b/tests-clar/diff/tree.c
@@ -19,7 +19,7 @@ void test_diff_tree__0(void)
 	const char *b_commit = "370fe9ec22";
 	const char *c_commit = "f5b0af1fb4f5c";
 	git_tree *a, *b, *c;
-	git_diff_options opts = {0};
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	git_diff_list *diff = NULL;
 	diff_expects exp;
 
@@ -175,7 +175,7 @@ void test_diff_tree__bare(void)
 	const char *a_commit = "8496071c1b46c85";
 	const char *b_commit = "be3563ae3f79";
 	git_tree *a, *b;
-	git_diff_options opts = {0};
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	git_diff_list *diff = NULL;
 	diff_expects exp;
 
@@ -264,7 +264,7 @@ void test_diff_tree__larger_hunks(void)
 	const char *a_commit = "d70d245ed97ed2aa596dd1af6536e4bfdb047b69";
 	const char *b_commit = "7a9e0b02e63179929fed24f0a3e0f19168114d10";
 	git_tree *a, *b;
-	git_diff_options opts = {0};
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	git_diff_list *diff = NULL;
 	size_t d, num_d, h, num_h, l, num_l, header_len, line_len;
 	const git_diff_delta *delta;
@@ -319,3 +319,31 @@ void test_diff_tree__larger_hunks(void)
 	git_tree_free(a);
 	git_tree_free(b);
 }
+
+void test_diff_tree__checks_options_version(void)
+{
+	const char *a_commit = "8496071c1b46c85";
+	const char *b_commit = "be3563ae3f79";
+	git_tree *a, *b;
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
+	git_diff_list *diff = NULL;
+	const git_error *err;
+
+	g_repo = cl_git_sandbox_init("testrepo.git");
+
+	cl_assert((a = resolve_commit_oid_to_tree(g_repo, a_commit)) != NULL);
+	cl_assert((b = resolve_commit_oid_to_tree(g_repo, b_commit)) != NULL);
+
+	opts.version = 0;
+	cl_git_fail(git_diff_tree_to_tree(&diff, g_repo, a, b, &opts));
+	err = giterr_last();
+	cl_assert_equal_i(GITERR_INVALID, err->klass);
+
+	giterr_clear();
+	opts.version = 1024;
+	cl_git_fail(git_diff_tree_to_tree(&diff, g_repo, a, b, &opts));
+	err = giterr_last();
+
+	git_tree_free(a);
+	git_tree_free(b);
+}
diff --git a/tests-clar/diff/workdir.c b/tests-clar/diff/workdir.c
index 57c88c3..10d58b1 100644
--- a/tests-clar/diff/workdir.c
+++ b/tests-clar/diff/workdir.c
@@ -15,7 +15,7 @@ void test_diff_workdir__cleanup(void)
 
 void test_diff_workdir__to_index(void)
 {
-	git_diff_options opts = {0};
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	git_diff_list *diff = NULL;
 	diff_expects exp;
 	int use_iterator;
@@ -69,7 +69,7 @@ void test_diff_workdir__to_tree(void)
 	const char *a_commit = "26a125ee1bf"; /* the current HEAD */
 	const char *b_commit = "0017bd4ab1ec3"; /* the start */
 	git_tree *a, *b;
-	git_diff_options opts = {0};
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	git_diff_list *diff = NULL;
 	git_diff_list *diff2 = NULL;
 	diff_expects exp;
@@ -202,7 +202,7 @@ void test_diff_workdir__to_tree(void)
 
 void test_diff_workdir__to_index_with_pathspec(void)
 {
-	git_diff_options opts = {0};
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	git_diff_list *diff = NULL;
 	diff_expects exp;
 	char *pathspec = NULL;
@@ -420,7 +420,7 @@ void test_diff_workdir__filemode_changes_with_filemode_false(void)
 
 void test_diff_workdir__head_index_and_workdir_all_differ(void)
 {
-	git_diff_options opts = {0};
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	git_diff_list *diff_i2t = NULL, *diff_w2i = NULL;
 	diff_expects exp;
 	char *pathspec = "staged_changes_modified_file";
@@ -518,7 +518,7 @@ void test_diff_workdir__head_index_and_workdir_all_differ(void)
 
 void test_diff_workdir__eof_newline_changes(void)
 {
-	git_diff_options opts = {0};
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	git_diff_list *diff = NULL;
 	diff_expects exp;
 	char *pathspec = "current_file";
@@ -678,7 +678,7 @@ void test_diff_workdir__larger_hunks(void)
 	const char *a_commit = "d70d245ed97ed2aa596dd1af6536e4bfdb047b69";
 	const char *b_commit = "7a9e0b02e63179929fed24f0a3e0f19168114d10";
 	git_tree *a, *b;
-	git_diff_options opts = {0};
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	size_t i, d, num_d, h, num_h, l, num_l, header_len, line_len;
 
 	g_repo = cl_git_sandbox_init("diff");
@@ -763,7 +763,7 @@ void test_diff_workdir__submodules(void)
 {
 	const char *a_commit = "873585b94bdeabccea991ea5e3ec1a277895b698";
 	git_tree *a;
-	git_diff_options opts = {0};
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	git_diff_list *diff = NULL;
 	diff_expects exp;
 
@@ -822,7 +822,7 @@ void test_diff_workdir__submodules(void)
 
 void test_diff_workdir__cannot_diff_against_a_bare_repository(void)
 {
-	git_diff_options opts = {0};
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	git_diff_list *diff = NULL;
 	git_tree *tree;
 
@@ -843,7 +843,7 @@ void test_diff_workdir__to_null_tree(void)
 {
 	git_diff_list *diff;
 	diff_expects exp;
-	git_diff_options opts = {0};
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 
 	opts.flags = GIT_DIFF_INCLUDE_UNTRACKED |
 		GIT_DIFF_RECURSE_UNTRACKED_DIRS;
@@ -861,3 +861,23 @@ void test_diff_workdir__to_null_tree(void)
 
 	git_diff_list_free(diff);
 }
+
+void test_diff_workdir__checks_options_version(void)
+{
+	git_diff_list *diff;
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
+	const git_error *err;
+
+	g_repo = cl_git_sandbox_init("status");
+
+	opts.version = 0;
+	cl_git_fail(git_diff_workdir_to_tree(&diff, g_repo, NULL, &opts));
+	err = giterr_last();
+	cl_assert_equal_i(GITERR_INVALID, err->klass);
+
+	giterr_clear();
+	opts.version = 1024;
+	cl_git_fail(git_diff_workdir_to_tree(&diff, g_repo, NULL, &opts));
+	err = giterr_last();
+	cl_assert_equal_i(GITERR_INVALID, err->klass);
+}
diff --git a/tests-clar/network/fetch.c b/tests-clar/network/fetch.c
index 623352f..33c2293 100644
--- a/tests-clar/network/fetch.c
+++ b/tests-clar/network/fetch.c
@@ -36,10 +36,9 @@ static void progress(const git_transfer_progress *stats, void *payload)
 static void do_fetch(const char *url, git_remote_autotag_option_t flag, int n)
 {
 	git_remote *remote;
-	git_remote_callbacks callbacks;
+	git_remote_callbacks callbacks = GIT_REMOTE_CALLBACKS_INIT;
 	size_t bytes_received = 0;
 
-	memset(&callbacks, 0, sizeof(git_remote_callbacks));
 	callbacks.update_tips = update_tips;
 	counter = 0;
 
@@ -78,6 +77,7 @@ void test_network_fetch__no_tags_http(void)
 
 static void transferProgressCallback(const git_transfer_progress *stats, void *payload)
 {
+	GIT_UNUSED(stats);
 	bool *invoked = (bool *)payload;
 
 	GIT_UNUSED(stats);
diff --git a/tests-clar/network/push_util.h b/tests-clar/network/push_util.h
index 2f4dffc..759122a 100644
--- a/tests-clar/network/push_util.h
+++ b/tests-clar/network/push_util.h
@@ -11,7 +11,8 @@ extern const git_oid OID_ZERO;
  * record data in a record_callbacks_data instance.
  * @param data pointer to a record_callbacks_data instance
  */
-#define RECORD_CALLBACKS_INIT(data) { NULL, NULL, record_update_tips_cb, data }
+#define RECORD_CALLBACKS_INIT(data) \
+	{ GIT_REMOTE_CALLBACKS_VERSION, NULL, NULL, record_update_tips_cb, data }
 
 typedef struct {
 	char *name;
diff --git a/tests-clar/network/remotes.c b/tests-clar/network/remotes.c
index b4a3ad9..70df001 100644
--- a/tests-clar/network/remotes.c
+++ b/tests-clar/network/remotes.c
@@ -306,3 +306,23 @@ void test_network_remotes__cannot_load_with_an_empty_url(void)
 	cl_git_fail(git_remote_load(&remote, _repo, "empty-remote-url"));
 	cl_assert(giterr_last()->klass == GITERR_INVALID);
 }
+
+void test_network_remotes__check_structure_version(void)
+{
+	git_transport transport = GIT_TRANSPORT_INIT;
+	const git_error *err;
+
+	git_remote_free(_remote);
+	cl_git_pass(git_remote_new(&_remote, _repo, NULL, "test-protocol://localhost", NULL));
+
+	transport.version = 0;
+	cl_git_fail(git_remote_set_transport(_remote, &transport));
+	err = giterr_last();
+	cl_assert_equal_i(GITERR_INVALID, err->klass);
+
+	giterr_clear();
+	transport.version = 1024;
+	cl_git_fail(git_remote_set_transport(_remote, &transport));
+	err = giterr_last();
+	cl_assert_equal_i(GITERR_INVALID, err->klass);
+}
diff --git a/tests-clar/odb/sorting.c b/tests-clar/odb/sorting.c
index bf64f6a..b4f9e44 100644
--- a/tests-clar/odb/sorting.c
+++ b/tests-clar/odb/sorting.c
@@ -11,11 +11,11 @@ static git_odb_backend *new_backend(int position)
 {
 	fake_backend *b;
 
-	b = git__malloc(sizeof(fake_backend));
+	b = git__calloc(1, sizeof(fake_backend));
 	if (b == NULL)
 		return NULL;
 
-	memset(b, 0x0, sizeof(fake_backend));
+	b->base.version = GIT_ODB_BACKEND_VERSION;
 	b->position = position;
 	return (git_odb_backend *)b;
 }
diff --git a/tests-clar/refs/branches/tracking.c b/tests-clar/refs/branches/tracking.c
index 7af5f97..bc41e06 100644
--- a/tests-clar/refs/branches/tracking.c
+++ b/tests-clar/refs/branches/tracking.c
@@ -65,7 +65,8 @@ static void assert_merge_and_or_remote_key_missing(git_repository *repository, c
 {
 	git_reference *branch;
 
-	cl_git_pass(git_branch_create(&branch, repository, entry_name, target, 0));
+	cl_assert_equal_i(GIT_OBJ_COMMIT, git_object_type(target));
+	cl_git_pass(git_branch_create(&branch, repository, entry_name, (git_commit*)target, 0));
 
 	cl_assert_equal_i(GIT_ENOTFOUND, git_branch_tracking(&tracking, branch));
 
diff --git a/tests-clar/repo/init.c b/tests-clar/repo/init.c
index 3b14c97..c0acbed 100644
--- a/tests-clar/repo/init.c
+++ b/tests-clar/repo/init.c
@@ -304,8 +304,7 @@ void test_repo_init__sets_logAllRefUpdates_according_to_type_of_repository(void)
 
 void test_repo_init__extended_0(void)
 {
-	git_repository_init_options opts;
-	memset(&opts, 0, sizeof(opts));
+	git_repository_init_options opts = GIT_REPOSITORY_INIT_OPTIONS_INIT;
 
 	/* without MKDIR this should fail */
 	cl_git_fail(git_repository_init_ext(&_repo, "extended", &opts));
@@ -327,8 +326,7 @@ void test_repo_init__extended_1(void)
 	git_reference *ref;
 	git_remote *remote;
 	struct stat st;
-	git_repository_init_options opts;
-	memset(&opts, 0, sizeof(opts));
+	git_repository_init_options opts = GIT_REPOSITORY_INIT_OPTIONS_INIT;
 
 	opts.flags = GIT_REPOSITORY_INIT_MKPATH |
 		GIT_REPOSITORY_INIT_NO_DOTGIT_DIR;
@@ -367,8 +365,7 @@ void test_repo_init__extended_1(void)
 
 void test_repo_init__extended_with_template(void)
 {
-	git_repository_init_options opts;
-	memset(&opts, 0, sizeof(opts));
+	git_repository_init_options opts = GIT_REPOSITORY_INIT_OPTIONS_INIT;
 
 	opts.flags = GIT_REPOSITORY_INIT_MKPATH | GIT_REPOSITORY_INIT_BARE;
 	opts.template_path = cl_fixture("template");
diff --git a/tests-clar/status/ignore.c b/tests-clar/status/ignore.c
index 27f9d85..e2e4aaf 100644
--- a/tests-clar/status/ignore.c
+++ b/tests-clar/status/ignore.c
@@ -180,9 +180,6 @@ void test_status_ignore__subdirectories(void)
 {
 	status_entry_single st;
 	int ignored;
-	git_status_options opts;
-
-	GIT_UNUSED(opts);
 
 	g_repo = cl_git_sandbox_init("empty_standard_repo");
 
@@ -216,11 +213,6 @@ void test_status_ignore__subdirectories(void)
 	cl_git_mkfile(
 		"empty_standard_repo/test/ignore_me/file", "I'm going to be ignored!");
 
-	opts.show = GIT_STATUS_SHOW_INDEX_AND_WORKDIR;
-	opts.flags = GIT_STATUS_OPT_INCLUDE_IGNORED |
-		GIT_STATUS_OPT_INCLUDE_UNTRACKED |
-		GIT_STATUS_OPT_RECURSE_UNTRACKED_DIRS;
-
 	memset(&st, 0, sizeof(st));
 	cl_git_pass(git_status_foreach(g_repo, cb_status__single, &st));
 	cl_assert_equal_i(2, st.count);
diff --git a/tests-clar/status/worktree.c b/tests-clar/status/worktree.c
index 7ae1883..a1f7f86 100644
--- a/tests-clar/status/worktree.c
+++ b/tests-clar/status/worktree.c
@@ -111,7 +111,7 @@ void test_status_worktree__swap_subdir_and_file(void)
 	status_entry_counts counts;
 	git_repository *repo = cl_git_sandbox_init("status");
 	git_index *index;
-	git_status_options opts;
+	git_status_options opts = GIT_STATUS_OPTIONS_INIT;
 	bool ignore_case;
 
 	cl_git_pass(git_repository_index(&index, repo));
@@ -133,7 +133,6 @@ void test_status_worktree__swap_subdir_and_file(void)
 	counts.expected_paths = ignore_case ? entry_paths3_icase : entry_paths3;
 	counts.expected_statuses = ignore_case ? entry_statuses3_icase : entry_statuses3;
 
-	memset(&opts, 0, sizeof(opts));
 	opts.flags = GIT_STATUS_OPT_INCLUDE_UNTRACKED |
 		GIT_STATUS_OPT_INCLUDE_IGNORED;
 
@@ -150,7 +149,7 @@ void test_status_worktree__swap_subdir_with_recurse_and_pathspec(void)
 {
 	status_entry_counts counts;
 	git_repository *repo = cl_git_sandbox_init("status");
-	git_status_options opts;
+	git_status_options opts = GIT_STATUS_OPTIONS_INIT;
 
 	/* first alter the contents of the worktree */
 	cl_git_pass(p_rename("status/current_file", "status/swap"));
@@ -167,7 +166,6 @@ void test_status_worktree__swap_subdir_with_recurse_and_pathspec(void)
 	counts.expected_paths = entry_paths4;
 	counts.expected_statuses = entry_statuses4;
 
-	memset(&opts, 0, sizeof(opts));
 	opts.flags = GIT_STATUS_OPT_INCLUDE_UNTRACKED |
 		GIT_STATUS_OPT_RECURSE_UNTRACKED_DIRS;
 	/* TODO: set pathspec to "current_file" eventually */
@@ -691,7 +689,7 @@ void test_status_worktree__filemode_changes(void)
 {
 	git_repository *repo = cl_git_sandbox_init("filemodes");
 	status_entry_counts counts;
-	git_status_options opts;
+	git_status_options opts = GIT_STATUS_OPTIONS_INIT;
 	git_config *cfg;
 
 	/* overwrite stored filemode with platform appropriate value */
@@ -708,7 +706,6 @@ void test_status_worktree__filemode_changes(void)
 				filemode_statuses[i] = GIT_STATUS_CURRENT;
 	}
 
-	memset(&opts, 0, sizeof(opts));
 	opts.flags = GIT_STATUS_OPT_INCLUDE_UNTRACKED |
 		GIT_STATUS_OPT_INCLUDE_IGNORED |
 		GIT_STATUS_OPT_INCLUDE_UNMODIFIED;
@@ -746,7 +743,7 @@ static int cb_status__expected_path(const char *p, unsigned int s, void *payload
 void test_status_worktree__disable_pathspec_match(void)
 {
 	git_repository *repo;
-	git_status_options opts;
+	git_status_options opts = GIT_STATUS_OPTIONS_INIT;
 	char *file_with_bracket = "LICENSE[1].md", 
 		*imaginary_file_with_bracket = "LICENSE[1-2].md";
 
@@ -754,7 +751,6 @@ void test_status_worktree__disable_pathspec_match(void)
 	cl_git_mkfile("pathspec/LICENSE[1].md", "screaming bracket\n");
 	cl_git_mkfile("pathspec/LICENSE1.md", "no bracket\n");
 
-	memset(&opts, 0, sizeof(opts));
 	opts.flags = GIT_STATUS_OPT_INCLUDE_UNTRACKED | 
 		GIT_STATUS_OPT_DISABLE_PATHSPEC_MATCH;
 	opts.pathspec.count = 1;