diff --git a/builtin/replace.c b/builtin/replace.c
index 3da1bae..0751804 100644
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -275,6 +275,9 @@
 
 	free(tmpfile);
 
+	if (!hashcmp(old, new))
+		return error("new object is the same as the old one: '%s'", sha1_to_hex(old));
+
 	return replace_object_sha1(object_ref, old, "replacement", new, force);
 }