diff --git a/patch-ids.h b/patch-ids.h
index c8c7ca1..eeb56b3 100644
--- a/patch-ids.h
+++ b/patch-ids.h
@@ -13,6 +13,8 @@
 	struct patch_id_bucket *patches;
 };
 
+int commit_patch_id(struct commit *commit, struct diff_options *options,
+		    unsigned char *sha1);
 int init_patch_ids(struct patch_ids *);
 int free_patch_ids(struct patch_ids *);
 struct patch_id *add_commit_patch_id(struct commit *, struct patch_ids *);