diff --git a/cgit.h b/cgit.h
index db9a8eb..b2253d2 100644
--- a/cgit.h
+++ b/cgit.h
@@ -340,6 +340,9 @@ extern int cgit_refs_cb(const char *refname, const struct object_id *oid,
 
 extern void *cgit_free_commitinfo(struct commitinfo *info);
 
+void cgit_diff_tree_cb(struct diff_queue_struct *q,
+		       struct diff_options *options, void *data);
+
 extern int cgit_diff_files(const unsigned char *old_sha1,
 			   const unsigned char *new_sha1,
 			   unsigned long *old_size, unsigned long *new_size,
diff --git a/shared.c b/shared.c
index a83afcb..0431b59 100644
--- a/shared.c
+++ b/shared.c
@@ -250,8 +250,8 @@ int cgit_refs_cb(const char *refname, const struct object_id *oid, int flags,
 	return 0;
 }
 
-static void cgit_diff_tree_cb(struct diff_queue_struct *q,
-			      struct diff_options *options, void *data)
+void cgit_diff_tree_cb(struct diff_queue_struct *q,
+		       struct diff_options *options, void *data)
 {
 	int i;