diff --git a/mrbgems/mruby-dir/src/dir.c b/mrbgems/mruby-dir/src/dir.c
index 499cd0766..3e12dda15 100644
--- a/mrbgems/mruby-dir/src/dir.c
+++ b/mrbgems/mruby-dir/src/dir.c
@@ -146,6 +146,12 @@ mrb_dir_getwd(mrb_state *mrb, mrb_value klass)
   return path;
 }
 
+#ifndef _WIN32
+#define MAKE_DIR(path, mode) mkdir(path, mode)
+#else
+#define MAKE_DIR(path, mode) mkdir(path)
+#endif
+
 mrb_value
 mrb_dir_mkdir(mrb_state *mrb, mrb_value klass)
 {
@@ -156,11 +162,7 @@ mrb_dir_mkdir(mrb_state *mrb, mrb_value klass)
   mode = 0777;
   mrb_get_args(mrb, "S|i", &spath, &mode);
   path = mrb_str_to_cstr(mrb, spath);
-#ifndef _WIN32
-  if (mkdir(path, mode) == -1) {
-#else
-  if (mkdir(path) == -1) {
-#endif
+  if (MAKE_DIR(path, mode) == -1) {
     mrb_sys_fail(mrb, path);
   }
   return mrb_fixnum_value(0);