diff --git a/src/js/background.js b/src/js/background.js
index 4ac91efc3..cbc12529a 100644
--- a/src/js/background.js
+++ b/src/js/background.js
@@ -19,6 +19,8 @@
     Home: https://github.com/gorhill/uBlock
 */
 
+/* globals browser */
+
 'use strict';
 
 /******************************************************************************/
@@ -149,7 +151,6 @@ const µBlock = {  // jshint ignore:line
     privacySettingsSupported: vAPI.browserSettings instanceof Object,
     cloudStorageSupported: vAPI.cloud instanceof Object,
     canFilterResponseData: typeof browser.webRequest.filterResponseData === 'function',
-    canInjectScriptletsNow: vAPI.webextFlavor.soup.has('chromium'),
 
     // https://github.com/chrisaljoudi/uBlock/issues/180
     // Whitelist directives need to be loaded once the PSL is available
diff --git a/src/js/contentscript.js b/src/js/contentscript.js
index cb75f8cc3..59045fd0f 100644
--- a/src/js/contentscript.js
+++ b/src/js/contentscript.js
@@ -1362,6 +1362,9 @@ vAPI.DOMFilterer = class {
         vAPI.messaging.send('contentscript', {
             what: 'retrieveContentScriptParameters',
             url: vAPI.effectiveSelf.location.href,
+            scriptletsInjected:
+                typeof self.uBO_scriptletsInjected === 'boolean' &&
+                self.uBO_scriptletsInjected,
         }).then(response => {
             bootstrapPhase1(response);
         });
diff --git a/src/js/messaging.js b/src/js/messaging.js
index 9de7ba6da..c920db9e4 100644
--- a/src/js/messaging.js
+++ b/src/js/messaging.js
@@ -773,10 +773,7 @@ const retrieveContentScriptParameters = async function(sender, request) {
     // https://github.com/uBlockOrigin/uBlock-issues/issues/688#issuecomment-748179731
     //   For non-network URIs, scriptlet injection is deferred to here. The
     //   effective URL is available here in `request.url`.
-    if (
-        µb.canInjectScriptletsNow === false ||
-        isNetworkURI(sender.frameURL) === false
-    ) {
+    if ( request.scriptletsInjected !== true ) {
         scriptletFilteringEngine.injectNow(request);
     }
 
diff --git a/src/js/scriptlet-filtering.js b/src/js/scriptlet-filtering.js
index 1e6c3b12d..8c2be9ba9 100644
--- a/src/js/scriptlet-filtering.js
+++ b/src/js/scriptlet-filtering.js
@@ -95,6 +95,7 @@ const contentscriptCode = (( ) => {
             ) {
                 return;
             }
+            self.uBO_scriptletsInjected = true;
             const injectScriptlets = function(d) {
                 let script;
                 try {
diff --git a/src/js/tab.js b/src/js/tab.js
index b28e7c6ad..48dd9e32b 100644
--- a/src/js/tab.js
+++ b/src/js/tab.js
@@ -41,7 +41,6 @@ import {
 import {
     domainFromHostname,
     hostnameFromURI,
-    isNetworkURI,
     originFromURI,
 } from './uri-utils.js';
 
@@ -930,11 +929,7 @@ vAPI.Tabs = class extends vAPI.Tabs {
         const pageStore = µb.pageStoreFromTabId(tabId);
         if ( pageStore === null ) { return; }
         pageStore.setFrameURL(details);
-        if (
-            µb.canInjectScriptletsNow &&
-            isNetworkURI(url) &&
-            pageStore.getNetFilteringSwitch()
-        ) {
+        if ( pageStore.getNetFilteringSwitch() ) {
             scriptletFilteringEngine.injectNow(details);
         }
     }