diff --git a/commit.h b/commit.h
index 936f8fce30..491b0c4aac 100644
--- a/commit.h
+++ b/commit.h
@@ -110,7 +110,7 @@ extern struct commit_list *get_merge_bases(struct commit *rev1, struct commit *r
 extern int register_shallow(const unsigned char *sha1);
 extern int unregister_shallow(const unsigned char *sha1);
 extern int write_shallow_commits(int fd, int use_pack_protocol);
-extern int is_repository_shallow();
+extern int is_repository_shallow(void);
 extern struct commit_list *get_shallow_commits(struct object_array *heads,
 		int depth, int shallow_flag, int not_shallow_flag);
 
diff --git a/shallow.c b/shallow.c
index 3d53d17423..d17868929c 100644
--- a/shallow.c
+++ b/shallow.c
@@ -17,7 +17,7 @@ int register_shallow(const unsigned char *sha1)
 	return register_commit_graft(graft, 0);
 }
 
-int is_repository_shallow()
+int is_repository_shallow(void)
 {
 	FILE *fp;
 	char buf[1024];