diff --git a/test/browser_test_helper.rb b/test/browser_test_helper.rb
index 4dd3f9a34..c66024eb8 100644
--- a/test/browser_test_helper.rb
+++ b/test/browser_test_helper.rb
@@ -77,7 +77,7 @@ class TestCase < Test::Unit::TestCase
   def screenshot(params)
     instance = params[:browser] || @browser
     comment = params[:comment] || ''
-    filename = "tmp/#{Time.zone.now.strftime("screenshot_%Y_%m_%d__%H_%M_%S")}_#{comment}_#{instance.hash}.png"
+    filename = "tmp/#{Time.zone.now.strftime('screenshot_%Y_%m_%d__%H_%M_%S')}_#{comment}_#{instance.hash}.png"
     log('screenshot', { filename: filename })
     instance.save_screenshot(filename)
   end