diff --git a/core/lib/Drupal/Core/Extension/ModuleHandler.php b/core/lib/Drupal/Core/Extension/ModuleHandler.php
index 8e1cdb6..1d9978f 100644
--- a/core/lib/Drupal/Core/Extension/ModuleHandler.php
+++ b/core/lib/Drupal/Core/Extension/ModuleHandler.php
@@ -242,6 +242,9 @@ public function resetImplementations() {
    * Implements \Drupal\Core\Extension\ModuleHandlerInterface::implementsHook().
    */
   public function implementsHook($module, $hook) {
+    if (!isset($this->moduleList[$module])) {
+      return FALSE;
+    }
     $function = $module . '_' . $hook;
     if (function_exists($function)) {
       return TRUE;