diff --git a/mrbgems/mruby-random/src/random.c b/mrbgems/mruby-random/src/random.c
index 025c4f369..98d4fce4d 100644
--- a/mrbgems/mruby-random/src/random.c
+++ b/mrbgems/mruby-random/src/random.c
@@ -349,20 +349,20 @@ mrb_ary_sample(mrb_state *mrb, mrb_value ary)
     if (n > len) n = len;
     result = mrb_ary_new_capa(mrb, n);
     for (mrb_int i=0; i<n; i++) {
-      mrb_int r;
+      mrb_int idx;
 
       for (;;) {
       retry:
-        r = rand_i(random, len);
+        idx = rand_i(random, len);
 
         for (mrb_int j=0; j<i; j++) {
-          if (mrb_integer(RARRAY_PTR(result)[j]) == r) {
+          if (mrb_integer(RARRAY_PTR(result)[j]) == idx) {
             goto retry;         /* retry if duplicate */
           }
         }
         break;
       }
-      mrb_ary_push(mrb, result, mrb_int_value(mrb, r));
+      mrb_ary_push(mrb, result, mrb_int_value(mrb, idx));
     }
     for (mrb_int i=0; i<n; i++) {
       mrb_int idx = mrb_integer(RARRAY_PTR(result)[i]);