diff --git a/awx/main/conf.py b/awx/main/conf.py
index 8a2b361ab6..bbdf159ae6 100644
--- a/awx/main/conf.py
+++ b/awx/main/conf.py
@@ -111,6 +111,7 @@ register(
     help_text=_('List of modules allowed to be used by ad-hoc jobs.'),
     category=_('Jobs'),
     category_slug='jobs',
+    required=False,
 )
 
 register(
diff --git a/awx/ui/client/src/configuration/configuration.controller.js b/awx/ui/client/src/configuration/configuration.controller.js
index 49a5f2ad99..05b5c2e576 100644
--- a/awx/ui/client/src/configuration/configuration.controller.js
+++ b/awx/ui/client/src/configuration/configuration.controller.js
@@ -364,7 +364,12 @@ export default [
                             payload[key] = _.map($scope[key], 'value').join(',');
                         }
                     } else {
-                        payload[key] = $scope[key].value;
+                        if(multiselectDropdowns.indexOf(key) !== -1) {
+                            // Default AD_HOC_COMMANDS to an empty list
+                            payload[key] = $scope[key].value || [];
+                        } else {
+                            payload[key] = $scope[key].value;
+                        }
                     }
                 } else if($scope.configDataResolve[key].type === 'list' && $scope[key] !== null) {
                     // Parse lists