diff --git a/lib/internal/errors.js b/lib/internal/errors.js
index 59785df7eb..d81a070a11 100755
--- a/lib/internal/errors.js
+++ b/lib/internal/errors.js
@@ -311,7 +311,7 @@ function invalidArgType(name, expected, actual) {
   let determiner;
   if (typeof expected === 'string' && expected.startsWith('not ')) {
     determiner = 'must not be';
-    expected = expected.split('not ')[1];
+    expected = expected.replace(/^not /, '');
   } else {
     determiner = 'must be';
   }