1 files changed, 2 insertions, 0 deletions
diff --git a/hash.c b/hash.c
index 70b6bd4ac9..91a4e9fea0 100644
--- a/hash.c
+++ b/hash.c
@@ -2288,6 +2288,8 @@ rb_hash_flatten(int argc, VALUE *argv, VALUE hash)
     return ary;
 }
 
+static VALUE rb_hash_compare_by_id_p(VALUE hash);
+
 /*
  *  call-seq:
  *     hsh.compare_by_identity -> hsh