diff --git a/static/js/directives/ui/trigger-setup-custom.js b/static/js/directives/ui/trigger-setup-custom.js
index b14899efd..60c57e2ea 100644
--- a/static/js/directives/ui/trigger-setup-custom.js
+++ b/static/js/directives/ui/trigger-setup-custom.js
@@ -35,6 +35,11 @@ angular.module('quay').directive('triggerSetupCustom', function() {
       });
 
       $scope.$watch('state.subdir', function(subdir) {
+        // Code elsewhere assumes root is empty string.
+        if (subdir === '/') {
+          subdir = '';
+        }
+
         $scope.trigger['config']['subdir'] = subdir;
         $scope.trigger.$ready = subdir != null;
       });