diff --git a/mrbgems/mruby-random/src/random.c b/mrbgems/mruby-random/src/random.c
index 9fb5bbfd8..5b291bf61 100644
--- a/mrbgems/mruby-random/src/random.c
+++ b/mrbgems/mruby-random/src/random.c
@@ -76,7 +76,7 @@ get_opt(mrb_state* mrb)
 {
   mrb_value arg;
 
-  arg = mrb_fixnum_value(0);
+  arg = mrb_nil_value();
   mrb_get_args(mrb, "|o", &arg);
 
   if (!mrb_nil_p(arg)) {