diff --git a/mrbgems/mruby-symbol-ext/src/symbol.c b/mrbgems/mruby-symbol-ext/src/symbol.c
index 4340d74a3..475d1f20a 100644
--- a/mrbgems/mruby-symbol-ext/src/symbol.c
+++ b/mrbgems/mruby-symbol-ext/src/symbol.c
@@ -25,13 +25,13 @@
 static mrb_value
 mrb_sym_all_symbols(mrb_state *mrb, mrb_value self)
 {
-  mrb_sym i, lim;
   mrb_value ary = mrb_ary_new_capa(mrb, mrb->symidx);
 
-  for (i=1; i<=MRB_PRESYM_MAX; i++) {
+  for (mrb_sym i=1; i<=MRB_PRESYM_MAX; i++) {
     mrb_ary_push(mrb, ary, mrb_symbol_value(i));
   }
-  for (i=1, lim=mrb->symidx+1; i<lim; i++) {
+  mrb_sym lim = mrb->symidx + 1;
+  for (mrb_sym i=1; i<lim; i++) {
     mrb_ary_push(mrb, ary, mrb_symbol_value(i+MRB_PRESYM_MAX));
   }