diff --git a/frontend_tests/casper_lib/common.js b/frontend_tests/casper_lib/common.js
index 39d4d862da..6af762363c 100644
--- a/frontend_tests/casper_lib/common.js
+++ b/frontend_tests/casper_lib/common.js
@@ -83,7 +83,7 @@ exports.then_log_in = function (credentials) {
 };
 
 exports.start_and_log_in = function (credentials, viewport) {
-    casper.start('http://localhost:9981/accounts/login', function () {
+    casper.start('http://127.0.0.1:9981/accounts/login', function () {
         exports.initialize_casper(viewport);
         log_in(credentials);
     });
diff --git a/frontend_tests/casper_tests/00-realm-creation.js b/frontend_tests/casper_tests/00-realm-creation.js
index 691785f14e..3058ee107e 100644
--- a/frontend_tests/casper_tests/00-realm-creation.js
+++ b/frontend_tests/casper_tests/00-realm-creation.js
@@ -4,7 +4,7 @@ var email = 'alice@test.example.com';
 var domain = 'test.example.com';
 var organization_name = 'Awesome Organization';
 
-casper.start('http://localhost:9981/create_realm/');
+casper.start('http://127.0.0.1:9981/create_realm/');
 
 casper.then(function () {
     // Submit the email for realm creation
@@ -21,12 +21,12 @@ casper.then(function () {
 });
 
 // Special endpoint enabled only during tests for extracting confirmation key
-casper.thenOpen('http://localhost:9981/confirmation_key/');
+casper.thenOpen('http://127.0.0.1:9981/confirmation_key/');
 
 // Open the confirmation URL
 casper.then(function () {
     var confirmation_key = JSON.parse(this.getPageContent()).confirmation_key;
-    var confirmation_url = 'http://localhost:9981/accounts/do_confirm/' + confirmation_key;
+    var confirmation_url = 'http://127.0.0.1:9981/accounts/do_confirm/' + confirmation_key;
     this.thenOpen(confirmation_url);
 });
 
@@ -56,7 +56,7 @@ casper.then(function () {
     });
 
     this.waitWhileSelector('form[action^="/accounts/register/"]', function () {
-        casper.test.assertUrlMatch('http://localhost:9981/invite/', 'Invite more users page loaded');
+        casper.test.assertUrlMatch('http://127.0.0.1:9981/invite/', 'Invite more users page loaded');
     });
 });
 
@@ -75,7 +75,7 @@ casper.then(function () {
     });
 
     this.waitWhileSelector('#submit_invitation', function () {
-        this.test.assertUrlMatch('http://localhost:9981/', 'Realm created and logged in');
+        this.test.assertUrlMatch('http://127.0.0.1:9981/', 'Realm created and logged in');
     });
 });
 
diff --git a/frontend_tests/casper_tests/01-login.js b/frontend_tests/casper_tests/01-login.js
index c085c5a310..b0a3489469 100644
--- a/frontend_tests/casper_tests/01-login.js
+++ b/frontend_tests/casper_tests/01-login.js
@@ -1,7 +1,7 @@
 var common = require('../casper_lib/common.js').common;
 
 // Start of test script.
-casper.start('http://localhost:9981/', common.initialize_casper);
+casper.start('http://127.0.0.1:9981/', common.initialize_casper);
 
 casper.then(function () {
     casper.test.assertHttpStatus(302);
diff --git a/frontend_tests/casper_tests/06-settings.js b/frontend_tests/casper_tests/06-settings.js
index aea1520d89..cac6dfe2fc 100644
--- a/frontend_tests/casper_tests/06-settings.js
+++ b/frontend_tests/casper_tests/06-settings.js
@@ -162,7 +162,7 @@ casper.waitForSelector("#default_language", function () {
     casper.test.info("Opening German page through i18n url.");
 });
 
-casper.thenOpen('http://localhost:9981/de/#settings');
+casper.thenOpen('http://127.0.0.1:9981/de/#settings');
 
 casper.waitForSelector("#settings-change-box", function check_url_preference() {
     casper.test.info("Checking the i18n url language precedence.");
diff --git a/frontend_tests/casper_tests/10-admin.js b/frontend_tests/casper_tests/10-admin.js
index 67157c07fa..e632853a7b 100644
--- a/frontend_tests/casper_tests/10-admin.js
+++ b/frontend_tests/casper_tests/10-admin.js
@@ -144,7 +144,7 @@ casper.then(function () {
     casper.waitForSelector('.admin-emoji-form', function () {
         casper.fill('form.admin-emoji-form', {
             'name': 'MouseFace',
-            'url': 'http://localhost:9991/static/images/integrations/logos/jenkins.png'
+            'url': 'http://127.0.0.1:9991/static/images/integrations/logos/jenkins.png'
         });
         casper.click('form.admin-emoji-form input.btn');
     });
@@ -159,7 +159,7 @@ casper.then(function () {
 casper.then(function () {
     casper.waitForSelector('.emoji_row', function () {
         casper.test.assertSelectorHasText('.emoji_row .emoji_name', 'MouseFace');
-        casper.test.assertExists('.emoji_row img[src="http://localhost:9991/static/images/integrations/logos/jenkins.png"]');
+        casper.test.assertExists('.emoji_row img[src="http://127.0.0.1:9991/static/images/integrations/logos/jenkins.png"]');
         casper.click('.emoji_row button.delete');
     });
 });
diff --git a/frontend_tests/run-casper b/frontend_tests/run-casper
index fc51fda311..0a2605a83c 100755
--- a/frontend_tests/run-casper
+++ b/frontend_tests/run-casper
@@ -25,7 +25,7 @@ except ImportError as e:
 # on how to use remote debugging
 #
 
-os.environ["TORNADO_SERVER"] = "http://localhost:9983"
+os.environ["TORNADO_SERVER"] = "http://127.0.0.1:9983"
 
 usage = """%prog [options]
     test-js-with-casper # Run all test files
@@ -60,7 +60,7 @@ def server_is_up(server):
     assert_server_running(server)
     try:
         # We could get a 501 error if the reverse proxy is up but the Django app isn't.
-        return requests.get('http://localhost:9981/accounts/home').status_code == 200
+        return requests.get('http://127.0.0.1:9981/accounts/home').status_code == 200
     except:
         return False