diff --git a/core/includes/install.inc b/core/includes/install.inc
index 7ceeeda..4436787 100644
--- a/core/includes/install.inc
+++ b/core/includes/install.inc
@@ -985,6 +985,11 @@ function drupal_check_module($module) {
   module_load_install($module);
   // Check requirements based on hook_requirements().
   $requirements = \Drupal::moduleHandler()->invoke($module, 'requirements', array('install'));
+  // Make sure the requirements are an array, even if the hook invocation
+  // returns NULL, because the module does not implement hook_requirements().
+  if (!is_array($requirements)) {
+    $requirements = [];
+  }
 
   // We can't use the module handler here because it only gives us enabled
   // extensions.