diff --git a/keepassxc-browser/content/keepassxc-browser.js b/keepassxc-browser/content/keepassxc-browser.js
index 7eb916d..60a4a47 100755
--- a/keepassxc-browser/content/keepassxc-browser.js
+++ b/keepassxc-browser/content/keepassxc-browser.js
@@ -151,6 +151,25 @@ kpxcForm.onSubmit = function() {
 var kpxcFields = {};
 
 kpxcFields.inputQueryPattern = 'input[type=\'text\'], input[type=\'email\'], input[type=\'password\'], input[type=\'tel\'], input[type=\'number\'], input:not([type])';
+
+// copied from Sizzle.js
+kpxcFields.rcssescape = /([\0-\x1f\x7f]|^-?\d)|^-$|[^\0-\x1f\x7f-\uFFFF\w-]/g;
+kpxcFields.fcssescape = function(ch, asCodePoint) {
+        if (asCodePoint) {
+
+             // U+0000 NULL becomes U+FFFD REPLACEMENT CHARACTER
+            if (ch === "\0") {
+                return "\uFFFD";
+            }
+
+             // Control characters and (dependent upon position) numbers get escaped as code points
+            return ch.slice(0, -1) + "\\" + ch.charCodeAt(ch.length - 1).toString(16) + " ";
+        }
+
+         // Other potentially-special ASCII characters get backslash-escaped
+        return "\\" + ch;
+    };
+
 // Unique number as new IDs for input fields
 kpxcFields.uniqueNumber = 342845638;
 // Objects with combination of username + password fields
@@ -175,9 +194,7 @@ kpxcFields.setUniqueId = function(field) {
 };
 
 kpxcFields.prepareId = function(id) {
-    return id.replace(/[:#.,\[\]\(\)' "]/g, function(m) {
-        return '\\' + m;
-    });
+    return (id + "").replace(kpxcFields.rcssescape, kpxcFields.fcssescape);
 };
 
 /**