diff --git a/mrbgems/mruby-sprintf/src/sprintf.c b/mrbgems/mruby-sprintf/src/sprintf.c
index fa195f7c4..71a3e90d4 100644
--- a/mrbgems/mruby-sprintf/src/sprintf.c
+++ b/mrbgems/mruby-sprintf/src/sprintf.c
@@ -1016,7 +1016,7 @@ retry:
 #else
         mrb_value val = GETARG();
         double fval;
-        int need = 6;
+        mrb_int need = 6;
 
         fval = mrb_as_float(mrb, val);
         if (!isfinite(fval)) {