diff --git a/core/tests/Drupal/KernelTests/Core/Image/ToolkitGdTest.php b/core/tests/Drupal/KernelTests/Core/Image/ToolkitGdTest.php
index 4fbd512..a7fb86f 100644
--- a/core/tests/Drupal/KernelTests/Core/Image/ToolkitGdTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Image/ToolkitGdTest.php
@@ -52,6 +52,11 @@ protected function setUp() {
 
     // Set the image factory service.
     $this->imageFactory = $this->container->get('image.factory');
+
+    // For PHP 7.1+, ensure test PHP has webp extension installed.
+    if (PHP_VERSION_ID >= 70100) {
+      $this->assertTrue(function_exists('imagewebp'));
+    }
   }
 
   protected function checkRequirements() {