diff --git a/lib/internal/process/main_thread_only.js b/lib/internal/process/main_thread_only.js
index 96c57fda35c755..2572402f620c27 100644
--- a/lib/internal/process/main_thread_only.js
+++ b/lib/internal/process/main_thread_only.js
@@ -26,11 +26,9 @@ function wrapProcessMethods(binding) {
   }
 
   function umask(mask) {
-    if (mask === undefined) {
-      // Get the mask
-      return binding.umask(mask);
+    if (mask !== undefined) {
+      mask = validateMode(mask, 'mask');
     }
-    mask = validateMode(mask, 'mask');
     return binding.umask(mask);
   }