diff --git a/src/js/scriptlet-filtering.js b/src/js/scriptlet-filtering.js
index 72dcc444a..1a8e2901f 100644
--- a/src/js/scriptlet-filtering.js
+++ b/src/js/scriptlet-filtering.js
@@ -91,7 +91,8 @@ const contentscriptCode = (( ) => {
         function(hostname, scriptlets) {
             if (
                 document.location === null ||
-                hostname !== document.location.hostname
+                hostname !== document.location.hostname ||
+                typeof self.uBO_scriptletsInjected === 'boolean'
             ) {
                 return;
             }