diff --git a/spec/core/ClockSpec.js b/spec/core/ClockSpec.js
index 0595ab05..e7f92811 100644
--- a/spec/core/ClockSpec.js
+++ b/spec/core/ClockSpec.js
@@ -5,7 +5,8 @@ describe("Clock", function() {
       fakeGlobal = { setTimeout: fakeSetTimeout },
       delayedFunctionScheduler = jasmine.createSpyObj("delayedFunctionScheduler", ["scheduleFunction"]),
       delayedFn = jasmine.createSpy("delayedFn"),
-      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler);
+      mockDate = { install: function() {}, tick: function() {}, uninstall: function() {} },
+      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler, mockDate);
 
     fakeGlobal.setTimeout(delayedFn, 0);
 
@@ -26,7 +27,8 @@ describe("Clock", function() {
       fakeGlobal = { clearTimeout: fakeClearTimeout },
       delayedFunctionScheduler = jasmine.createSpyObj("delayedFunctionScheduler", ["removeFunctionWithId"]),
       delayedFn = jasmine.createSpy("delayedFn"),
-      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler);
+      mockDate = { install: function() {}, tick: function() {}, uninstall: function() {} },
+      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler, mockDate);
 
     fakeGlobal.clearTimeout("foo");
 
@@ -47,7 +49,8 @@ describe("Clock", function() {
       fakeGlobal = { setInterval: fakeSetInterval },
       delayedFunctionScheduler = jasmine.createSpyObj("delayedFunctionScheduler", ["scheduleFunction"]),
       delayedFn = jasmine.createSpy("delayedFn"),
-      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler);
+      mockDate = { install: function() {}, tick: function() {}, uninstall: function() {} },
+      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler, mockDate);
 
     fakeGlobal.setInterval(delayedFn, 0);
 
@@ -68,7 +71,8 @@ describe("Clock", function() {
       fakeGlobal = { clearInterval: fakeClearInterval },
       delayedFunctionScheduler = jasmine.createSpyObj("delayedFunctionScheduler", ["removeFunctionWithId"]),
       delayedFn = jasmine.createSpy("delayedFn"),
-      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler);
+      mockDate = { install: function() {}, tick: function() {}, uninstall: function() {} },
+      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler, mockDate);
 
     fakeGlobal.clearInterval("foo");
 
@@ -97,7 +101,8 @@ describe("Clock", function() {
       },
       delayedFunctionScheduler = jasmine.createSpyObj("delayedFunctionScheduler", ["scheduleFunction", "reset"]),
       delayedFn = jasmine.createSpy("delayedFn"),
-      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler);
+      mockDate = { install: function() {}, tick: function() {}, uninstall: function() {} },
+      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler, mockDate);
 
     clock.install();
     clock.uninstall();
@@ -119,7 +124,8 @@ describe("Clock", function() {
       delayedFunctionScheduler = { scheduleFunction: scheduleFunction },
       fakeGlobal = { setTimeout: fakeSetTimeout },
       delayedFn = jasmine.createSpy('delayedFn'),
-      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler);
+      mockDate = { install: function() {}, tick: function() {}, uninstall: function() {} },
+      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler, mockDate);
 
     clock.install();
     clock.setTimeout(delayedFn, 0, 'a', 'b');
@@ -135,7 +141,8 @@ describe("Clock", function() {
       delayedFunctionScheduler = {scheduleFunction: scheduleFunction},
       fakeGlobal = { setTimeout: fakeSetTimeout },
       delayedFn = jasmine.createSpy('delayedFn'),
-      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler),
+      mockDate = { install: function() {}, tick: function() {}, uninstall: function() {} },
+      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler, mockDate),
       timeoutId;
 
     clock.install();
@@ -149,7 +156,8 @@ describe("Clock", function() {
       delayedFunctionScheduler = jasmine.createSpyObj('delayedFunctionScheduler', ['removeFunctionWithId']),
       fakeGlobal = { setTimeout: fakeClearTimeout },
       delayedFn = jasmine.createSpy('delayedFn'),
-      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler);
+      mockDate = { install: function() {}, tick: function() {}, uninstall: function() {} },
+      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler, mockDate);
 
     clock.install();
     clock.clearTimeout(123);
@@ -164,7 +172,8 @@ describe("Clock", function() {
       delayedFunctionScheduler = {scheduleFunction: scheduleFunction},
       fakeGlobal = { setInterval: fakeSetInterval },
       delayedFn = jasmine.createSpy('delayedFn'),
-      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler);
+      mockDate = { install: function() {}, tick: function() {}, uninstall: function() {} },
+      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler, mockDate);
 
     clock.install();
     clock.setInterval(delayedFn, 0, 'a', 'b');
@@ -180,7 +189,8 @@ describe("Clock", function() {
       delayedFunctionScheduler = {scheduleFunction: scheduleFunction},
       fakeGlobal = { setInterval: fakeSetInterval },
       delayedFn = jasmine.createSpy('delayedFn'),
-      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler),
+      mockDate = { install: function() {}, tick: function() {}, uninstall: function() {} },
+      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler, mockDate),
       intervalId;
 
     clock.install();
@@ -194,7 +204,8 @@ describe("Clock", function() {
       delayedFunctionScheduler = jasmine.createSpyObj('delayedFunctionScheduler', ['removeFunctionWithId']),
       fakeGlobal = { setInterval: clearInterval },
       delayedFn = jasmine.createSpy('delayedFn'),
-      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler);
+      mockDate = { install: function() {}, tick: function() {}, uninstall: function() {} },
+      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler, mockDate);
 
     clock.install();
     clock.clearInterval(123);
@@ -220,7 +231,8 @@ describe("Clock", function() {
         setTimeout: fakeSetTimeout,
         setInterval: fakeSetInterval
       },
-      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler);
+      mockDate = { install: function() {}, tick: function() {}, uninstall: function() {} },
+      clock = new j$.Clock(fakeGlobal, delayedFunctionScheduler, mockDate);
 
     fakeSetTimeout.apply = null;
     fakeSetInterval.apply = null;
@@ -249,7 +261,8 @@ describe("Clock (acceptance)", function() {
       delayedFn3 = jasmine.createSpy('delayedFn3'),
       recurring1 = jasmine.createSpy('recurring1'),
       delayedFunctionScheduler = new j$.DelayedFunctionScheduler(),
-      clock = new j$.Clock({setTimeout: setTimeout}, delayedFunctionScheduler);
+      mockDate = { install: function() {}, tick: function() {}, uninstall: function() {} },
+      clock = new j$.Clock({setTimeout: setTimeout}, delayedFunctionScheduler, mockDate);
 
     clock.install();
 
@@ -295,7 +308,8 @@ describe("Clock (acceptance)", function() {
   it("can clear a previously set timeout", function() {
     var clearedFn = jasmine.createSpy('clearedFn'),
       delayedFunctionScheduler = new j$.DelayedFunctionScheduler(),
-      clock = new j$.Clock({setTimeout: function() {}}, delayedFunctionScheduler),
+      mockDate = { install: function() {}, tick: function() {}, uninstall: function() {} },
+      clock = new j$.Clock({setTimeout: function() {}}, delayedFunctionScheduler, mockDate),
       timeoutId;
 
     clock.install();
@@ -312,7 +326,8 @@ describe("Clock (acceptance)", function() {
   it("correctly schedules functions after the Clock has advanced", function() {
     var delayedFn1 = jasmine.createSpy('delayedFn1'),
       delayedFunctionScheduler = new j$.DelayedFunctionScheduler(),
-      clock = new j$.Clock({setTimeout: function() {}}, delayedFunctionScheduler);
+      mockDate = { install: function() {}, tick: function() {}, uninstall: function() {} },
+      clock = new j$.Clock({setTimeout: function() {}}, delayedFunctionScheduler, mockDate);
 
     clock.install();
 
@@ -328,7 +343,8 @@ describe("Clock (acceptance)", function() {
     var delayedFn1 = jasmine.createSpy('delayedFn1'),
         delayedFn2 = jasmine.createSpy('delayedFn2'),
         delayedFunctionScheduler = new j$.DelayedFunctionScheduler(),
-        clock = new j$.Clock({setTimeout: function() {}}, delayedFunctionScheduler);
+        mockDate = { install: function() {}, tick: function() {}, uninstall: function() {} },
+        clock = new j$.Clock({setTimeout: function() {}}, delayedFunctionScheduler, mockDate);
 
     delayedFn1.and.callFake(function() { clock.setTimeout(delayedFn2, 0); });
     clock.install();
@@ -346,7 +362,8 @@ describe("Clock (acceptance)", function() {
     var delayedFn1 = jasmine.createSpy('delayedFn1'),
         delayedFn2 = jasmine.createSpy('delayedFn2'),
         delayedFunctionScheduler = new j$.DelayedFunctionScheduler(),
-        clock = new j$.Clock({setTimeout: function() {}}, delayedFunctionScheduler);
+        mockDate = { install: function() {}, tick: function() {}, uninstall: function() {} },
+        clock = new j$.Clock({setTimeout: function() {}}, delayedFunctionScheduler, mockDate);
 
     delayedFn1.and.callFake(function() { clock.setTimeout(delayedFn2, 1); });
     clock.install();
@@ -357,7 +374,7 @@ describe("Clock (acceptance)", function() {
     expect(delayedFn2).toHaveBeenCalled();  
   });
 
-  it("does not mock the Date object when installing without parameters", function() {
+  it("does not mock the Date object by default", function() {
      var delayedFunctionScheduler = new j$.DelayedFunctionScheduler(),
       global = {Date: Date},
       mockDate = new j$.MockDate(global),
@@ -367,30 +384,30 @@ describe("Clock (acceptance)", function() {
 
     expect(global.Date).toEqual(Date);
 
-    var now = global.Date.now();
+    var now = new global.Date().getTime();
 
     clock.tick(50);
 
-    expect(global.Date.now() - now).not.toEqual(50);
+    expect(new global.Date().getTime() - now).not.toEqual(50);
   });
 
-  it("mocks the Date object and sets it to current time when installing with true parameter", function() {
+  it("mocks the Date object and sets it to current time", function() {
     var delayedFunctionScheduler = new j$.DelayedFunctionScheduler(),
       global = {Date: Date},
       mockDate = new j$.MockDate(global),
       clock = new j$.Clock({setTimeout: setTimeout}, delayedFunctionScheduler, mockDate);
 
-    clock.install(true);
+    clock.install().mockDate();
 
-    var now = global.Date.now();
+    var now = new global.Date().getTime();
 
     clock.tick(50);
 
-    expect(global.Date.now() - now).toEqual(50);
+    expect(new global.Date().getTime() - now).toEqual(50);
 
     var timeoutDate = 0;
     clock.setTimeout(function() {
-      timeoutDate = global.Date.now();
+      timeoutDate = new global.Date().getTime();
     }, 100);
 
     clock.tick(100);
@@ -398,7 +415,7 @@ describe("Clock (acceptance)", function() {
     expect(timeoutDate - now).toEqual(150);
   });
 
-  it("mocks the Date object and sets it to a given time when installing with a Date parameter", function() {
+  it("mocks the Date object and sets it to a given time", function() {
     var delayedFunctionScheduler = new j$.DelayedFunctionScheduler(),
       global = {Date: Date},
       mockDate = new j$.MockDate(global),
@@ -406,19 +423,19 @@ describe("Clock (acceptance)", function() {
       baseTime = new Date(2013, 9, 23);
 
 
-    clock.install(baseTime);
+    clock.install().mockDate(baseTime);
 
-    var now = global.Date.now();
+    var now = new global.Date().getTime();
 
     expect(now).toEqual(baseTime.getTime());
 
     clock.tick(50);
 
-    expect(global.Date.now()).toEqual(baseTime.getTime() + 50);
+    expect(new global.Date().getTime()).toEqual(baseTime.getTime() + 50);
 
     var timeoutDate = 0;
     clock.setTimeout(function() {
-      timeoutDate = global.Date.now();
+      timeoutDate = new global.Date().getTime();
     }, 100);
 
     clock.tick(100);
diff --git a/spec/core/MockDateSpec.js b/spec/core/MockDateSpec.js
index 05bf86f9..72aa357b 100644
--- a/spec/core/MockDateSpec.js
+++ b/spec/core/MockDateSpec.js
@@ -3,84 +3,126 @@ describe("FakeDate", function() {
     var fakeGlobal = {},
       mockDate = new j$.MockDate(fakeGlobal);
 
-    mockDate.install();
-
-    fakeGlobal.Date = jasmine.createSpy("Date");
-
-    mockDate.tick(0);
-
-    expect(fakeGlobal.Date).not.toHaveBeenCalled();
+    expect(function() {
+      mockDate.install();
+      mockDate.tick(0);
+      mockDate.uninstall();
+    }).not.toThrow();
   });
 
-  it("does not replace global Date if it is not installed", function() {
-    var fakeDate = jasmine.createSpy("global Date"),
-      fakeGlobal = { Date: fakeDate },
+  it("replaces the global Date when it is installed", function() {
+    var globalDate = jasmine.createSpy("global Date").and.callFake(function() {
+        return {
+          getTime: function() {}
+        }
+      }),
+      fakeGlobal = { Date: globalDate },
       mockDate = new j$.MockDate(fakeGlobal);
 
-    fakeDate.now = function(){};
-
-    expect(fakeDate).toEqual(fakeGlobal.Date);
+    expect(fakeGlobal.Date).toEqual(globalDate);
     mockDate.install();
 
-    expect(fakeDate).not.toEqual(fakeGlobal.Date);
+    expect(fakeGlobal.Date).not.toEqual(globalDate);
   });
 
   it("replaces the global Date on uninstall", function() {
-    var fakeDate = jasmine.createSpy("global Date"),
-      fakeGlobal = { Date: fakeDate },
+    var globalDate = jasmine.createSpy("global Date").and.callFake(function() {
+        return {
+          getTime: function() {}
+        }
+      }),
+      fakeGlobal = { Date: globalDate },
       mockDate = new j$.MockDate(fakeGlobal);
 
-    fakeDate.now = function(){};
-
     mockDate.install();
     mockDate.uninstall();
 
-    expect(fakeDate).toEqual(fakeGlobal.Date);
-
+    expect(fakeGlobal.Date).toEqual(globalDate);
   });
 
   it("takes the current time as the base when installing without parameters", function() {
-    var fakeDate = jasmine.createSpy("global Date"),
-      fakeGlobal = { Date: fakeDate },
+    var globalDate = jasmine.createSpy("global Date").and.callFake(function() {
+        return {
+          getTime: function() {
+            return 1000;
+          }
+        }
+      }),
+      fakeGlobal = { Date: globalDate },
       mockDate = new j$.MockDate(fakeGlobal);
 
-    fakeGlobal.Date.prototype.getTime = function() {
-      return 1000;
-    };
-    fakeDate.now = function(){ return 1000; };
-
     mockDate.install();
 
-    expect(new fakeGlobal.Date().getTime()).toEqual(1000);
+    globalDate.calls.reset();
+    new fakeGlobal.Date();
+    expect(globalDate).toHaveBeenCalledWith(1000);
   });
 
   it("can accept a date as time base when installing", function() {
     var fakeGlobal = { Date: Date },
       mockDate = new j$.MockDate(fakeGlobal),
-      baseDate = new Date(2013, 9, 23);
+      baseDate = new Date();
 
+    spyOn(baseDate, 'getTime').and.returnValue(123);
     mockDate.install(baseDate);
 
-    expect(new fakeGlobal.Date().getTime()).toEqual(baseDate.getTime());
+    expect(new fakeGlobal.Date().getTime()).toEqual(123);
   });
 
+  it("makes real dates", function() {
+    var fakeGlobal = { Date: Date },
+      mockDate = new j$.MockDate(fakeGlobal);
+
+    mockDate.install();
+    expect(new fakeGlobal.Date()).toEqual(jasmine.any(Date));
+  });
 
   it("fakes current time when using Date.now()", function() {
-    var fakeGlobal = { Date: Date },
-      mockDate = new j$.MockDate(fakeGlobal),
-      baseDate = new Date(2013, 9, 23);
+    var globalDate = jasmine.createSpy("global Date").and.callFake(function() {
+        return {
+          getTime: function() {
+            return 1000;
+          }
+        }
+      }),
+      fakeGlobal = { Date: globalDate };
 
-    mockDate.install(baseDate);
+    globalDate.now = function() {};
+    var mockDate = new j$.MockDate(fakeGlobal);
 
-    expect(fakeGlobal.Date.now()).toEqual(baseDate.getTime());
+    mockDate.install();
+
+    expect(fakeGlobal.Date.now()).toEqual(1000);
+  });
+
+  it("does not stub Date.now() if it doesn't already exist", function() {
+    var globalDate = jasmine.createSpy("global Date").and.callFake(function() {
+        return {
+          getTime: function() {
+            return 1000;
+          }
+        }
+      }),
+      fakeGlobal = { Date: globalDate },
+      mockDate = new j$.MockDate(fakeGlobal);
+
+    mockDate.install();
+
+    expect(fakeGlobal.Date.now).toThrowError("Browser does not support Date.now()");
   });
 
   it("makes time passes using tick", function() {
-    var fakeDate = jasmine.createSpy("global Date"),
-      fakeGlobal = { Date: fakeDate },
-      mockDate = new j$.MockDate(fakeGlobal);
+    var globalDate = jasmine.createSpy("global Date").and.callFake(function() {
+        return {
+          getTime: function() {
+            return 1000;
+          }
+        }
+      }),
+      fakeGlobal = { Date: globalDate };
 
-    fakeDate.now = function(){ return 1000; };
+    globalDate.now = function() {};
+    var mockDate = new j$.MockDate(fakeGlobal);
 
     mockDate.install();
 
@@ -94,11 +136,17 @@ describe("FakeDate", function() {
   });
 
   it("allows to increase 0 milliseconds using tick", function() {
-    var fakeDate = jasmine.createSpy("global Date"),
-      fakeGlobal = { Date: fakeDate },
-      mockDate = new j$.MockDate(fakeGlobal);
+    var globalDate = jasmine.createSpy("global Date").and.callFake(function() {
+        return {
+          getTime: function() {
+            return 1000;
+          }
+        }
+      }),
+      fakeGlobal = { Date: globalDate };
 
-    fakeDate.now = function(){ return 1000; };
+    globalDate.now = function() {};
+    var mockDate = new j$.MockDate(fakeGlobal);
 
     mockDate.install();
 
@@ -109,7 +157,7 @@ describe("FakeDate", function() {
     expect(fakeGlobal.Date.now()).toEqual(1000);
   });
 
-  it("allows to create a Date in a different time than now", function() {
+  it("allows to create a Date in a different time than the mocked time", function() {
     var fakeGlobal = { Date: Date },
       mockDate = new j$.MockDate(fakeGlobal),
       baseDate = new Date(2013, 9, 23, 0, 0, 0, 0);
@@ -117,22 +165,14 @@ describe("FakeDate", function() {
     mockDate.install(baseDate);
 
     var otherDate = new fakeGlobal.Date(2013, 9, 23, 0, 0, 1, 0);
-
-    mockDate.tick(1000);
-
-    expect(fakeGlobal.Date.now()).toEqual(otherDate.getTime());
+    expect(otherDate.getTime()).not.toEqual(baseDate.getTime());
   });
 
   it("copies all Date properties to the mocked date", function() {
     var fakeGlobal = { Date: Date },
-      mockDate = new j$.MockDate(fakeGlobal),
-      baseDate = new Date(2013, 9, 23, 0, 0, 0, 0);
+      mockDate = new j$.MockDate(fakeGlobal);
 
-    mockDate.install(baseDate);
-
-    var otherDate = new fakeGlobal.Date();
-
-    expect(otherDate).toEqual(jasmine.any(Date));
+    mockDate.install();
 
     expect(fakeGlobal.Date.UTC(2013, 9, 23)).toEqual(Date.UTC(2013, 9, 23));
   });
diff --git a/src/core/Clock.js b/src/core/Clock.js
index c05f2a97..1ca84708 100644
--- a/src/core/Clock.js
+++ b/src/core/Clock.js
@@ -1,5 +1,5 @@
 getJasmineRequireObj().Clock = function() {
-  function Clock(global, delayedFunctionScheduler, date) {
+  function Clock(global, delayedFunctionScheduler, mockDate) {
     var self = this,
       realTimingFunctions = {
         setTimeout: global.setTimeout,
@@ -17,27 +17,27 @@ getJasmineRequireObj().Clock = function() {
       timer;
 
 
-    self.install = function(mockDate) {
+    self.install = function() {
       replace(global, fakeTimingFunctions);
       timer = fakeTimingFunctions;
       installed = true;
 
-      if (date && mockDate) {
-        date.install(mockDate);
-      }
+      return self;
     };
 
     self.uninstall = function() {
       delayedFunctionScheduler.reset();
-      if (date) {
-        date.uninstall();
-      }
+      mockDate.uninstall();
       replace(global, realTimingFunctions);
 
       timer = realTimingFunctions;
       installed = false;
     };
 
+    self.mockDate = function(initialDate) {
+      mockDate.install(initialDate);
+    };
+
     self.setTimeout = function(fn, delay, params) {
       if (legacyIE()) {
         if (arguments.length > 2) {
@@ -68,9 +68,7 @@ getJasmineRequireObj().Clock = function() {
 
     self.tick = function(millis) {
       if (installed) {
-        if (date) {
-          date.tick(millis);
-        }
+        mockDate.tick(millis);
         delayedFunctionScheduler.tick(millis);
       } else {
         throw new Error('Mock clock is not installed, use jasmine.clock().install()');
diff --git a/src/core/MockDate.js b/src/core/MockDate.js
index 294579bb..bab3b751 100644
--- a/src/core/MockDate.js
+++ b/src/core/MockDate.js
@@ -13,10 +13,10 @@ getJasmineRequireObj().MockDate = function() {
     var GlobalDate = global.Date;
 
     self.install = function(mockDate) {
-      if (mockDate instanceof Date) {
+      if (mockDate instanceof GlobalDate) {
         currentTime = mockDate.getTime();
       } else {
-        currentTime = GlobalDate.now();
+        currentTime = new GlobalDate().getTime();
       }
 
       global.Date = FakeDate;
@@ -48,7 +48,11 @@ getJasmineRequireObj().MockDate = function() {
     function createDateProperties() {
 
       FakeDate.now = function() {
-        return currentTime;
+        if (GlobalDate.now) {
+          return currentTime;
+        } else {
+          throw new Error("Browser does not support Date.now()");
+        }
       };
 
       FakeDate.toSource = GlobalDate.toSource;