thodg/libgit2

diff --git a/src/clone.c b/src/clone.c
index 80a13d0..9dfc22c 100644
--- a/src/clone.c
+++ b/src/clone.c
@@ -50,7 +50,7 @@ static int create_tracking_branch(git_repository *repo, const git_oid *target, c
 			git_buf merge_target = GIT_BUF_INIT;
 			if (!git_buf_printf(&remote, "branch.%s.remote", name) &&
 				 !git_buf_printf(&merge, "branch.%s.merge", name) &&
-				 !git_buf_printf(&merge_target, "refs/heads/%s", name) &&
+				 !git_buf_printf(&merge_target, GIT_REFS_HEADS_DIR "%s", name) &&
 				 !git_config_set_string(cfg, git_buf_cstr(&remote), "origin") &&
 				 !git_config_set_string(cfg, git_buf_cstr(&merge), git_buf_cstr(&merge_target))) {
 				retcode = 0;
@@ -77,7 +77,7 @@ static int reference_matches_remote_head(const char *head_name, void *payload)
 	if (!git_reference_name_to_oid(&oid, head_info->repo, head_name) &&
 		 !git_oid_cmp(&head_info->remote_head_oid, &oid)) {
 		git_buf_puts(&head_info->branchname,
-						 head_name+strlen("refs/remotes/origin/"));
+						 head_name+strlen(GIT_REFS_REMOTES_DIR "origin/"));
 	}
 	return 0;
 }
@@ -90,7 +90,7 @@ static int update_head_to_new_branch(git_repository *repo, const git_oid *target
 		git_reference *head;
 		if (!git_reference_lookup(&head, repo, GIT_HEAD_FILE)) {
 			git_buf targetbuf = GIT_BUF_INIT;
-			if (!git_buf_printf(&targetbuf, "refs/heads/%s", name)) {
+			if (!git_buf_printf(&targetbuf, GIT_REFS_HEADS_DIR "%s", name)) {
 				retcode = git_reference_set_target(head, git_buf_cstr(&targetbuf));
 			}
 			git_buf_free(&targetbuf);
@@ -115,7 +115,7 @@ static int update_head_to_remote(git_repository *repo, git_remote *remote)
 	head_info.repo = repo;
 
 	/* Check to see if "master" matches the remote head */
-	if (!git_reference_name_to_oid(&oid, repo, "refs/remotes/origin/master") &&
+	if (!git_reference_name_to_oid(&oid, repo, GIT_REFS_REMOTES_DIR "origin/master") &&
 		 !git_oid_cmp(&remote_head->oid, &oid)) {
 		retcode = update_head_to_new_branch(repo, &oid, "master");
 	}
diff --git a/src/refs.c b/src/refs.c
index bd6fbee..2a3b8dd 100644
--- a/src/refs.c
+++ b/src/refs.c
@@ -1404,7 +1404,7 @@ int git_reference_rename(git_reference *ref, const char *new_name, int force)
 		git_reference_free(head);
 		head = NULL;
 
-		if (git_reference_create_symbolic(&head, ref->owner, "HEAD", new_name, 1) < 0) {
+		if (git_reference_create_symbolic(&head, ref->owner, GIT_HEAD_FILE, new_name, 1) < 0) {
 			giterr_set(GITERR_REFERENCE,
 				"Failed to update HEAD after renaming reference");
 			goto cleanup;
diff --git a/src/repository.c b/src/repository.c
index 1a46db0..1641129 100644
--- a/src/repository.c
+++ b/src/repository.c
@@ -654,10 +654,10 @@ static int repo_init_create_head(const char *git_dir, const char *ref_name)
 	if (!ref_name)
 		ref_name = GIT_BRANCH_MASTER;
 
-	if (git__prefixcmp(ref_name, "refs/") == 0)
+	if (git__prefixcmp(ref_name, GIT_REFS_DIR) == 0)
 		fmt = "ref: %s\n";
 	else
-		fmt = "ref: refs/heads/%s\n";
+		fmt = "ref: " GIT_REFS_HEADS_DIR "%s\n";
 
 	if (git_filebuf_printf(&ref, fmt, ref_name) < 0 ||
 		git_filebuf_commit(&ref, GIT_REFS_FILE_MODE) < 0)
@@ -1219,7 +1219,7 @@ int git_repository_is_empty(git_repository *repo)
 	git_reference *head = NULL, *branch = NULL;
 	int error;
 
-	if (git_reference_lookup(&head, repo, "HEAD") < 0)
+	if (git_reference_lookup(&head, repo, GIT_HEAD_FILE) < 0)
 		return -1;
 
 	if (git_reference_type(head) != GIT_REF_SYMBOLIC) {
@@ -1227,7 +1227,7 @@ int git_repository_is_empty(git_repository *repo)
 		return 0;
 	}
 
-	if (strcmp(git_reference_target(head), "refs/heads/master") != 0) {
+	if (strcmp(git_reference_target(head), GIT_REFS_HEADS_DIR "master") != 0) {
 		git_reference_free(head);
 		return 0;
 	}
diff --git a/src/revparse.c b/src/revparse.c
index 5e2db99..191f637 100644
--- a/src/revparse.c
+++ b/src/revparse.c
@@ -28,11 +28,11 @@ static int disambiguate_refname(git_reference **out, git_repository *repo, const
 
 	static const char* formatters[] = {
 		"%s",
-		"refs/%s",
-		"refs/tags/%s",
-		"refs/heads/%s",
-		"refs/remotes/%s",
-		"refs/remotes/%s/HEAD",
+		GIT_REFS_DIR "%s",
+		GIT_REFS_TAGS_DIR "%s",
+		GIT_REFS_HEADS_DIR "%s",
+		GIT_REFS_REMOTES_DIR "%s",
+		GIT_REFS_REMOTES_DIR "%s/" GIT_HEAD_FILE,
 		NULL
 	};
 
@@ -520,7 +520,7 @@ static int handle_grep_syntax(git_object **out, git_repository *repo, const git_
 
 	if (spec_oid == NULL) {
 		// TODO: @carlosmn: The glob should be refs/* but this makes git_revwalk_next() fails
-		if (git_revwalk_push_glob(walk, "refs/heads/*") < 0)
+		if (git_revwalk_push_glob(walk, GIT_REFS_HEADS_DIR "*") < 0)
 			goto cleanup;
 	} else if (git_revwalk_push(walk, spec_oid) < 0)
 			goto cleanup;
diff --git a/src/submodule.c b/src/submodule.c
index a216249..1805286 100644
--- a/src/submodule.c
+++ b/src/submodule.c
@@ -1315,7 +1315,7 @@ static int lookup_head_remote(git_buf *url, git_repository *repo)
 	/* remote should refer to something like refs/remotes/ORIGIN/BRANCH */
 
 	if (git_reference_type(remote) != GIT_REF_SYMBOLIC ||
-		git__prefixcmp(git_reference_target(remote), "refs/remotes/") != 0)
+		git__prefixcmp(git_reference_target(remote), GIT_REFS_REMOTES_DIR) != 0)
 	{
 		giterr_set(GITERR_SUBMODULE,
 			"Cannot resolve relative URL when HEAD is not symbolic");
@@ -1323,7 +1323,7 @@ static int lookup_head_remote(git_buf *url, git_repository *repo)
 		goto cleanup;
 	}
 
-	scan = tgt = git_reference_target(remote) + strlen("refs/remotes/");
+	scan = tgt = git_reference_target(remote) + strlen(GIT_REFS_REMOTES_DIR);
 	while (*scan && (*scan != '/' || (scan > tgt && scan[-1] != '\\')))
 		scan++; /* find non-escaped slash to end ORIGIN name */