1 files changed, 1 insertions, 5 deletions
diff --git a/src/array.c b/src/array.c
index 2fb662c92..0a99040c0 100644
--- a/src/array.c
+++ b/src/array.c
@@ -1031,11 +1031,7 @@ mrb_ary_join_m(mrb_state *mrb, mrb_value ary)
 {
   mrb_value sep = mrb_nil_value();
 
-  mrb_get_args(mrb, "|o", &sep);
-  if (!(mrb_nil_p(sep) || mrb_type(sep) == MRB_TT_STRING)) {
-    mrb_raise(mrb, E_TYPE_ERROR, "expected String");
-    return mrb_nil_value();
-  }
+  mrb_get_args(mrb, "|S!", &sep);
   return mrb_ary_join(mrb, ary, sep);
 }