diff --git a/lib/jasmine-core/jasmine.js b/lib/jasmine-core/jasmine.js
index a5614f9d..3460c7c9 100644
--- a/lib/jasmine-core/jasmine.js
+++ b/lib/jasmine-core/jasmine.js
@@ -1721,11 +1721,15 @@ if (typeof window == void 0 && typeof exports == "object") {
 }
 
 getJasmineRequireObj().Timer = function() {
+  var defaultNow = (function(Date) {
+    return function() { return new Date().getTime(); };
+  })(Date);
+
   function Timer(options) {
     options = options || {};
 
-    var now = options.now || function() { return new Date().getTime(); },
-        startTime;
+    var now = options.now || defaultNow,
+      startTime;
 
     this.start = function() {
       startTime = now();
diff --git a/src/core/Timer.js b/src/core/Timer.js
index 92cc97b1..f8270f41 100644
--- a/src/core/Timer.js
+++ b/src/core/Timer.js
@@ -1,9 +1,13 @@
 getJasmineRequireObj().Timer = function() {
+  var defaultNow = (function(Date) {
+    return function() { return new Date().getTime(); };
+  })(Date);
+
   function Timer(options) {
     options = options || {};
 
-    var now = options.now || function() { return new Date().getTime(); },
-        startTime;
+    var now = options.now || defaultNow,
+      startTime;
 
     this.start = function() {
       startTime = now();