diff --git a/src/util/minimal.js b/src/util/minimal.js
index 41f327c2f..559aac7c9 100644
--- a/src/util/minimal.js
+++ b/src/util/minimal.js
@@ -52,7 +52,9 @@ util.emptyObject = Object.freeze ? Object.freeze({}) : /* istanbul ignore next *
  * @type {boolean}
  * @const
  */
-util.isNode = Boolean(process && process.versions && process.versions.node);
+util.isNode = Boolean(typeof process !== "undefined" && process &&
+                      typeof process.versions !== "undefined" && process.versions &&
+                      process.versions.node);
 
 /**
  * Tests if the specified value is an integer.