diff --git a/commit.c b/commit.c
index 632061c2c3..731191e63b 100644
--- a/commit.c
+++ b/commit.c
@@ -224,7 +224,7 @@ int unregister_shallow(const unsigned char *sha1)
 	if (pos < 0)
 		return -1;
 	if (pos + 1 < commit_graft_nr)
-		memcpy(commit_graft + pos, commit_graft + pos + 1,
+		memmove(commit_graft + pos, commit_graft + pos + 1,
 				sizeof(struct commit_graft *)
 				* (commit_graft_nr - pos - 1));
 	commit_graft_nr--;