diff --git a/config/environments/test.rb b/config/environments/test.rb
index 68c74dab..7f2ca59e 100644
--- a/config/environments/test.rb
+++ b/config/environments/test.rb
@@ -11,6 +11,13 @@ Osem::Application.configure do
   config.serve_static_files = true
   config.static_cache_control = 'public, max-age=3600'
 
+  # Use memory store for assets cache intest to avoid caching to tmp/assets,
+  # because it causes hiding of deprecation messages in stylesheets, and
+  # reduces performance.
+  config.assets.configure do |env|
+    env.cache = ActiveSupport::Cache.lookup_store(:memory_store)
+  end
+
   # Do not eager load code on boot.
   config.eager_load = false
 
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index d9283117..92420826 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -59,7 +59,13 @@ RSpec.configure do |config|
   Capybara.javascript_driver = :poltergeist
 
   Capybara.register_driver :poltergeist do |app|
-    Capybara::Poltergeist::Driver.new(app, phantomjs: Phantomjs.path, js_errors: false, window_size: [1920, 1080])
+    Capybara::Poltergeist::Driver.new(
+      app,
+      phantomjs:     Phantomjs.path,
+      js_errors:     false,
+      window_size:   [1920, 1080],
+      url_whitelist: ['http://www.example.com']
+    )
   end
 
   # Includes helpers and connect them to specific types of tests