diff --git a/client/karma.js b/client/karma.js
index 20a5e19e0..5586bdc9e 100644
--- a/client/karma.js
+++ b/client/karma.js
@@ -5,7 +5,6 @@ var util = require('../common/util')
 function Karma (updater, socket, iframe, opener, navigator, location, document) {
   this.updater = updater
   var startEmitted = false
-  var karmaNavigating = false
   var self = this
   var queryParams = util.parseQueryParams(location.search)
   var browserId = queryParams.id || util.generateId('manual-')
@@ -83,21 +82,21 @@ function Karma (updater, socket, iframe, opener, navigator, location, document)
 
   var childWindow = null
   function navigateContextTo (url) {
-    karmaNavigating = true
     if (self.config.useIframe === false) {
       // run in new window
       if (self.config.runInParent === false) {
         // If there is a window already open, then close it
         // DEV: In some environments (e.g. Electron), we don't have setter access for location
         if (childWindow !== null && childWindow.closed !== true) {
+          // The onbeforeunload listener was added by context to catch
+          // unexpected navigations while running tests.
+          childWindow.onbeforeunload = undefined
           childWindow.close()
         }
         childWindow = opener(url)
-        karmaNavigating = false
       // run context on parent element (client_with_context)
       // using window.__karma__.scriptUrls to get the html element strings and load them dynamically
       } else if (url !== 'about:blank') {
-        karmaNavigating = false
         var loadScript = function (idx) {
           if (idx < window.__karma__.scriptUrls.length) {
             var parser = new DOMParser()
@@ -128,15 +127,10 @@ function Karma (updater, socket, iframe, opener, navigator, location, document)
       }
     // run in iframe
     } else {
+      // The onbeforeunload listener was added by the context to catch
+      // unexpected navigations while running tests.
+      iframe.contentWindow.onbeforeunload = undefined
       iframe.src = policy.createURL(url)
-      karmaNavigating = false
-    }
-  }
-
-  this.onbeforeunload = function () {
-    if (!karmaNavigating) {
-      // TODO(vojta): show what test (with explanation about jasmine.UPDATE_INTERVAL)
-      self.error('Some of your tests did a full page reload!')
     }
   }
 
diff --git a/context/karma.js b/context/karma.js
index 677767c9a..859d56d19 100644
--- a/context/karma.js
+++ b/context/karma.js
@@ -77,9 +77,9 @@ function ContextKarma (callParentKarmaMethod) {
     contextWindow.onerror = function () {
       return self.error.apply(self, arguments)
     }
-    // DEV: We must defined a function since we don't want to pass the event object
-    contextWindow.onbeforeunload = function (e, b) {
-      callParentKarmaMethod('onbeforeunload', [])
+
+    contextWindow.onbeforeunload = function () {
+      return self.error('Some of your tests did a full page reload!')
     }
 
     contextWindow.dump = function () {
diff --git a/static/context.js b/static/context.js
index 8cc67ebf6..417503165 100644
--- a/static/context.js
+++ b/static/context.js
@@ -214,9 +214,9 @@ function ContextKarma (callParentKarmaMethod) {
     contextWindow.onerror = function () {
       return self.error.apply(self, arguments)
     }
-    // DEV: We must defined a function since we don't want to pass the event object
-    contextWindow.onbeforeunload = function (e, b) {
-      callParentKarmaMethod('onbeforeunload', [])
+
+    contextWindow.onbeforeunload = function () {
+      return self.error('Some of your tests did a full page reload!')
     }
 
     contextWindow.dump = function () {
diff --git a/static/karma.js b/static/karma.js
index 1c1111450..23b7c1ae2 100644
--- a/static/karma.js
+++ b/static/karma.js
@@ -15,7 +15,6 @@ var util = require('../common/util')
 function Karma (updater, socket, iframe, opener, navigator, location, document) {
   this.updater = updater
   var startEmitted = false
-  var karmaNavigating = false
   var self = this
   var queryParams = util.parseQueryParams(location.search)
   var browserId = queryParams.id || util.generateId('manual-')
@@ -93,21 +92,21 @@ function Karma (updater, socket, iframe, opener, navigator, location, document)
 
   var childWindow = null
   function navigateContextTo (url) {
-    karmaNavigating = true
     if (self.config.useIframe === false) {
       // run in new window
       if (self.config.runInParent === false) {
         // If there is a window already open, then close it
         // DEV: In some environments (e.g. Electron), we don't have setter access for location
         if (childWindow !== null && childWindow.closed !== true) {
+          // The onbeforeunload listener was added by context to catch
+          // unexpected navigations while running tests.
+          childWindow.onbeforeunload = undefined
           childWindow.close()
         }
         childWindow = opener(url)
-        karmaNavigating = false
       // run context on parent element (client_with_context)
       // using window.__karma__.scriptUrls to get the html element strings and load them dynamically
       } else if (url !== 'about:blank') {
-        karmaNavigating = false
         var loadScript = function (idx) {
           if (idx < window.__karma__.scriptUrls.length) {
             var parser = new DOMParser()
@@ -138,15 +137,10 @@ function Karma (updater, socket, iframe, opener, navigator, location, document)
       }
     // run in iframe
     } else {
+      // The onbeforeunload listener was added by the context to catch
+      // unexpected navigations while running tests.
+      iframe.contentWindow.onbeforeunload = undefined
       iframe.src = policy.createURL(url)
-      karmaNavigating = false
-    }
-  }
-
-  this.onbeforeunload = function () {
-    if (!karmaNavigating) {
-      // TODO(vojta): show what test (with explanation about jasmine.UPDATE_INTERVAL)
-      self.error('Some of your tests did a full page reload!')
     }
   }
 
diff --git a/test/client/karma.spec.js b/test/client/karma.spec.js
index b1c50a00a..cb95ced81 100644
--- a/test/client/karma.spec.js
+++ b/test/client/karma.spec.js
@@ -22,7 +22,7 @@ describe('Karma', function () {
       }
     }
     socket = new MockSocket()
-    iframe = {}
+    iframe = { contentWindow: {} }
     windowNavigator = {}
     windowLocation = { search: '' }
     windowStub = sinon.stub().returns({})