That's the refdb, it's not the odb...
diff --git a/include/git2/sys/refdb_backend.h b/include/git2/sys/refdb_backend.h
index e0a24f4..addaa86 100644
--- a/include/git2/sys/refdb_backend.h
+++ b/include/git2/sys/refdb_backend.h
@@ -121,8 +121,8 @@ struct git_refdb_backend {
void (*free)(git_refdb_backend *backend);
};
-#define GIT_ODB_BACKEND_VERSION 1
-#define GIT_ODB_BACKEND_INIT {GIT_ODB_BACKEND_VERSION}
+#define GIT_REFDB_BACKEND_VERSION 1
+#define GIT_REFDB_BACKEND_INIT {GIT_REFDB_BACKEND_VERSION}
/**
* Constructors for default filesystem-based refdb backend