diff --git a/background/style-via-webrequest.js b/background/style-via-webrequest.js
index 4c02b612..9c27740e 100644
--- a/background/style-via-webrequest.js
+++ b/background/style-via-webrequest.js
@@ -154,8 +154,10 @@
 
   /** @param {chrome.webRequest.WebRequestBodyDetails} req */
   function openNamedStyle(req) {
-    chrome.tabs.update(req.tabId, {url: 'edit.html?id=' + req.url.split('#')[1]});
-    return {cancel: true};
+    if (!req.url.includes('?')) { // skipping our usercss installer
+      chrome.tabs.update(req.tabId, {url: 'edit.html?id=' + req.url.split('#')[1]});
+      return {cancel: true};
+    }
   }
 
   function req2key(req) {
diff --git a/content/style-injector.js b/content/style-injector.js
index 2ed4874b..ceeb1c60 100644
--- a/content/style-injector.js
+++ b/content/style-injector.js
@@ -158,7 +158,7 @@ window.StyleInjector = window.INJECTED === 1 ? window.StyleInjector : ({
   function setTextAndName(el, {id, code = '', name}) {
     if (exposeStyleName && name) {
       el.dataset.name = name;
-      name = encodeURIComponent(name.replace(/[#%/@:']/g, toSafeChar));
+      name = encodeURIComponent(name.replace(/[?#%/@:']/g, toSafeChar));
       code += `\n/*# sourceURL=${chrome.runtime.getURL(name)}.user.css#${id} */`;
     }
     el.textContent = code;