diff --git a/cache.h b/cache.h
index ee2db602bc..849bc0dcdd 100644
--- a/cache.h
+++ b/cache.h
@@ -1545,7 +1545,6 @@ extern struct alternate_object_database {
 	char path[FLEX_ARRAY];
 } *alt_odb_list;
 extern void prepare_alt_odb(void);
-extern void read_info_alternates(const char * relative_base, int depth);
 extern char *compute_alternate_path(const char *path, struct strbuf *err);
 typedef int alt_odb_fn(struct alternate_object_database *, void *);
 extern int foreach_alt_odb(alt_odb_fn, void*);
diff --git a/sha1_file.c b/sha1_file.c
index 4c4a1f1ea3..4fa4b185f3 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -347,6 +347,7 @@ static int alt_odb_usable(struct strbuf *path, const char *normalized_objdir)
  * SHA1, an extra slash for the first level indirection, and the
  * terminating NUL.
  */
+static void read_info_alternates(const char * relative_base, int depth);
 static int link_alt_odb_entry(const char *entry, const char *relative_base,
 	int depth, const char *normalized_objdir)
 {
@@ -448,7 +449,7 @@ static void link_alt_odb_entries(const char *alt, int len, int sep,
 	strbuf_release(&objdirbuf);
 }
 
-void read_info_alternates(const char * relative_base, int depth)
+static void read_info_alternates(const char * relative_base, int depth)
 {
 	char *map;
 	size_t mapsz;