diff --git a/lib/internal/errors.js b/lib/internal/errors.js
index 5a3aaa04e97a09..6a52d55bb84247 100644
--- a/lib/internal/errors.js
+++ b/lib/internal/errors.js
@@ -270,12 +270,14 @@ class AssertionError extends Error {
     if (message != null) {
       super(message);
     } else {
-      const util = lazyUtil();
-      if (process.stdout.isTTY && process.stdout.getColorDepth() !== 1) {
+      if (util_ === null &&
+          process.stdout.isTTY &&
+          process.stdout.getColorDepth() !== 1) {
         green = '\u001b[32m';
         white = '\u001b[39m';
         red = '\u001b[31m';
       }
+      const util = lazyUtil();
 
       if (actual && actual.stack && actual instanceof Error)
         actual = `${actual.name}: ${actual.message}`;