diff --git a/core/modules/language/src/Tests/LanguageConfigurationTest.php b/core/modules/language/src/Tests/LanguageConfigurationTest.php
index 025da77..8648328 100644
--- a/core/modules/language/src/Tests/LanguageConfigurationTest.php
+++ b/core/modules/language/src/Tests/LanguageConfigurationTest.php
@@ -91,6 +91,12 @@ function testLanguageConfiguration() {
     $this->drupalPostForm(NULL, $edit, t('Save configuration'));
     $this->assertFieldByXPath('//input[@name="prefix[fr]"]', 'french', 'French path prefix has changed.');
 
+    // Check that the prefix can be removed.
+    $edit = array(
+      'prefix[fr]' => '',
+    );
+    $this->drupalPostForm(NULL, $edit, t('Save configuration'));
+    $this->assertNoText(t('The prefix may only be left blank for the selected detection fallback language.'), 'The path prefix can be removed for the default language');
 
     // Change default negotiation language.
     $this->config('language.negotiation')->set('selected_langcode', 'fr')->save();