diff --git a/src/js/reverselookup-worker.js b/src/js/reverselookup-worker.js
index e8dedb915..8d04148fc 100644
--- a/src/js/reverselookup-worker.js
+++ b/src/js/reverselookup-worker.js
@@ -100,11 +100,13 @@ var fromCosmeticFilter = function(details) {
         prefix = match[0],
         filter = details.rawFilter.slice(prefix.length);
 
+    // https://github.com/gorhill/uBlock/issues/3101
+    //   Use `m` flag for efficient regex execution.
     var reFilter = new RegExp(
-            '[^\\n]*\\\\*"' +
+            '^\\[\\d,[^\\n]*\\\\*"' +
             reEscapeCosmetic(filter) +
-            '\\\\*"[^\\n]*',
-            'g'
+            '\\\\*"[^\\n]*\\]$',
+            'gm'
         );
 
     var reHostname = new RegExp(