diff --git a/src/hash.c b/src/hash.c
index bafeff4a7..ffef172b5 100644
--- a/src/hash.c
+++ b/src/hash.c
@@ -1274,6 +1274,7 @@ mrb_hash_set(mrb_state *mrb, mrb_value hash, mrb_value key, mrb_value val)
   mrb_field_write_barrier_value(mrb, mrb_basic_ptr(hash), key);
   mrb_field_write_barrier_value(mrb, mrb_basic_ptr(hash), val);
 }
+
 static void
 hash_set_default_proc(mrb_state *mrb, mrb_value hash, mrb_value proc)
 {
@@ -1493,11 +1494,12 @@ mrb_hash_set_default_proc(mrb_state *mrb, mrb_value hash)
   mrb_value ifnone = mrb_get_arg1(mrb);
 
   hash_modify(mrb, hash);
-  if (!mrb_nil_p(ifnone)) {
+  mrb_bool has_ifnone = !mrb_nil_p(ifnone);
+  if (has_ifnone) {
     mrb_check_type(mrb, ifnone, MRB_TT_PROC);
   }
   mrb_iv_set(mrb, hash, MRB_SYM(ifnone), ifnone);
-  if (!mrb_nil_p(ifnone)) {
+  if (has_ifnone) {
     hash_set_default_proc(mrb, hash, ifnone);
   }
   else {