diff --git a/lib/fs.js b/lib/fs.js
index 1fd40b9f4fcada..9aa4eaa6a562ec 100644
--- a/lib/fs.js
+++ b/lib/fs.js
@@ -536,8 +536,8 @@ fs.readFileSync = function(path, options) {
 
 // Used by binding.open and friends
 function stringToFlags(flag) {
-  // Only mess with strings
-  if (typeof flag !== 'string') {
+  // Return early if it's a number
+  if (typeof flag === 'number') {
     return flag;
   }