1 files changed, 1 insertions, 0 deletions
diff --git a/hash.c b/hash.c
index 7a6bfe8134..d49d0ea71d 100644
--- a/hash.c
+++ b/hash.c
@@ -1073,6 +1073,7 @@ replace_i(VALUE key, VALUE val, VALUE hash)
 static VALUE
 rb_hash_replace(VALUE hash, VALUE hash2)
 {
+    rb_hash_modify_check(hash);
     hash2 = to_hash(hash2);
     if (hash == hash2) return hash;
     rb_hash_clear(hash);