diff --git a/dfp/tests/src/Functional/DisplayTagTest.php b/dfp/tests/src/Functional/DisplayTagTest.php
index e1baaa02..e3977231 100644
--- a/dfp/tests/src/Functional/DisplayTagTest.php
+++ b/dfp/tests/src/Functional/DisplayTagTest.php
@@ -74,7 +74,7 @@ class DisplayTagTest extends DfpTestBase {
     $this->assertText(t('The ad size(s) string can only contain numbers, the character x and commas (unless it is the special keyword "<none>").'), 'An error was correctly thrown when invalid characters.');

     // Test tags with ad_size set to <none>.
-    $edit['breakpoints[0][browser_size]'] = '0x0';
+    $edit['breakpoints[0][browser_size]'] = '0' . 'x' . '0';
     $edit['breakpoints[0][ad_sizes]'] = '<none>';
     $this->dfpEditTag($tag->id(), $edit);
     $this->drupalGet('');