diff --git a/lib/utils.js b/lib/utils.js
index ac785b14b..3b99e637a 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -451,6 +451,10 @@ function deepMergeProperty(base, extras) {
   return mergedProperty;
 }
 
+const numberIsFinite = Number.isFinite || function(value) {
+  return typeof value === 'number' && isFinite(value);
+};
+
 /**
  * Adds a property __rank to array elements of type object {}
  * If an inner element already has the __rank property it is not altered
@@ -461,7 +465,7 @@ function deepMergeProperty(base, extras) {
  * @return rankedArray The original array with newly ranked elements
  */
 function rankArrayElements(array, rank) {
-  if (!Array.isArray(array) || !Number.isFinite(rank))
+  if (!Array.isArray(array) || !numberIsFinite(rank))
     return array;
 
   array.forEach(function(el) {