diff --git a/platform/chromium/manifest.json b/platform/chromium/manifest.json
index e35bd0d00..034114a4e 100644
--- a/platform/chromium/manifest.json
+++ b/platform/chromium/manifest.json
@@ -38,7 +38,7 @@
     "content_scripts": [
         {
             "matches": ["http://*/*", "https://*/*"],
-            "js": ["js/vapi-client.js", "js/vapi-usercss.js", "js/contentscript.js"],
+            "js": ["js/vapi-client.js", "js/contentscript.js"],
             "run_at": "document_start",
             "all_frames": true
         },
diff --git a/platform/firefox/frameModule.js b/platform/firefox/frameModule.js
index c99da7eeb..03ef0bebd 100644
--- a/platform/firefox/frameModule.js
+++ b/platform/firefox/frameModule.js
@@ -566,7 +566,6 @@ var contentObserver = {
         let sandbox = this.initContentScripts(win, true);
         try {
             lss(this.contentBaseURI + 'vapi-client.js', sandbox);
-            lss(this.contentBaseURI + 'vapi-usercss.js', sandbox);
             lss(this.contentBaseURI + 'contentscript.js', sandbox);
         } catch (ex) {
             //console.exception(ex.msg, ex.stack);
diff --git a/platform/webext/manifest.json b/platform/webext/manifest.json
index c9fd692d3..fe121d7db 100644
--- a/platform/webext/manifest.json
+++ b/platform/webext/manifest.json
@@ -38,7 +38,6 @@
          ],
          "js":[
             "js/vapi-client.js",
-            "js/vapi-usercss.js",
             "js/contentscript.js"
          ],
          "run_at":"document_start",
diff --git a/tools/make-chromium.sh b/tools/make-chromium.sh
index bf019146f..b6d9d2aab 100755
--- a/tools/make-chromium.sh
+++ b/tools/make-chromium.sh
@@ -24,6 +24,13 @@ cp platform/chromium/*.html $DES/
 cp platform/chromium/*.json $DES/
 cp LICENSE.txt              $DES/
 
+echo "*** uBlock0.chromium: concatenating content scripts"
+cat $DES/js/vapi-usercss.js > /tmp/contentscript.js
+echo >> /tmp/contentscript.js
+grep -v "^'use strict';$" $DES/js/contentscript.js >> /tmp/contentscript.js
+mv /tmp/contentscript.js $DES/js/contentscript.js
+rm $DES/js/vapi-usercss.js
+
 echo "*** uBlock0.chromium: Generating meta..."
 python tools/make-chromium-meta.py $DES/
 
diff --git a/tools/make-firefox.sh b/tools/make-firefox.sh
index 32dddba7a..f1b5f5ba6 100755
--- a/tools/make-firefox.sh
+++ b/tools/make-firefox.sh
@@ -31,6 +31,13 @@ cp    platform/firefox/install.rdf      $DES/
 cp    platform/firefox/*.xul            $DES/
 cp    LICENSE.txt                       $DES/
 
+echo "*** uBlock0.firefox: concatenating content scripts"
+cat $DES/js/vapi-usercss.js > /tmp/contentscript.js
+echo >> /tmp/contentscript.js
+grep -v "^'use strict';$" $DES/js/contentscript.js >> /tmp/contentscript.js
+mv /tmp/contentscript.js $DES/js/contentscript.js
+rm $DES/js/vapi-usercss.js
+
 echo "*** uBlock0.firefox: Generating meta..."
 python tools/make-firefox-meta.py $DES/
 
diff --git a/tools/make-webext.sh b/tools/make-webext.sh
index 4e37a7be6..a1e1b8266 100755
--- a/tools/make-webext.sh
+++ b/tools/make-webext.sh
@@ -32,6 +32,13 @@ cp platform/webext/vapi-usercss.js      $DES/js/
 rm $DES/options_ui.html
 rm $DES/js/options_ui.js
 
+echo "*** uBlock0.webext: concatenating content scripts"
+cat $DES/js/vapi-usercss.js > /tmp/contentscript.js
+echo >> /tmp/contentscript.js
+grep -v "^'use strict';$" $DES/js/contentscript.js >> /tmp/contentscript.js
+mv /tmp/contentscript.js $DES/js/contentscript.js
+rm $DES/js/vapi-usercss.js
+
 echo "*** uBlock0.webext: Generating meta..."
 python tools/make-webext-meta.py $DES/