diff --git a/build/files.js b/build/files.js
index f4c667a6da..f386ddda5c 100644
--- a/build/files.js
+++ b/build/files.js
@@ -333,7 +333,7 @@ const util = require('util')
     /$/,
     `
 
-if (util && util.inspect.custom) {
+if (util && util.inspect && util.inspect.custom) {
   module.exports.prototype[util.inspect.custom] = function () {
     const obj = util.inspect({ length: this.length });
     return \`\${this.constructor.name} \${obj}\`;
diff --git a/lib/internal/streams/BufferList.js b/lib/internal/streams/BufferList.js
index f061d4c50a..aefc68bd90 100644
--- a/lib/internal/streams/BufferList.js
+++ b/lib/internal/streams/BufferList.js
@@ -71,7 +71,7 @@ module.exports = function () {
   return BufferList;
 }();
 
-if (util && util.inspect.custom) {
+if (util && util.inspect && util.inspect.custom) {
   module.exports.prototype[util.inspect.custom] = function () {
     var obj = util.inspect({ length: this.length });
     return this.constructor.name + ' ' + obj;