diff --git a/src/js/reverselookup-worker.js b/src/js/reverselookup-worker.js
index 5278e97cf..a1e1535cd 100644
--- a/src/js/reverselookup-worker.js
+++ b/src/js/reverselookup-worker.js
@@ -216,8 +216,8 @@ let fromCosmeticFilter = function(details) {
                 break;
             // Specific cosmetic filtering
             case 8:
-                if ( exception !== ((fargs[1] & 0b01) !== 0) ) { break; }
-                isProcedural = (fargs[1] & 0b10) !== 0;
+                if ( exception !== ((fargs[1] & 0b0001) !== 0) ) { break; }
+                isProcedural = (fargs[1] & 0b0010) !== 0;
                 if (
                     isProcedural === false && fargs[3] !== selector ||
                     isProcedural && JSON.parse(fargs[3]).raw !== selector
@@ -230,7 +230,7 @@ let fromCosmeticFilter = function(details) {
                 break;
             // Scriptlet injection
             case 32:
-                if ( exception !== (fargs[1].charAt(0) === '!') ) { break; }
+                if ( exception !== ((fargs[1] & 0b0001) !== 0) ) { break; }
                 if ( fargs[3] !== selector ) { break; }
                 if ( hostnameMatches(fargs[2]) ) {
                     found = fargs[2] + prefix + selector;
@@ -239,7 +239,7 @@ let fromCosmeticFilter = function(details) {
             // HTML filtering
             case 64: // CSS selector
             case 65: // procedural
-                if ( exception !== (fargs[1].charAt(0) === '!') ) { break; }
+                if ( exception !== ((fargs[1] & 0b0001) !== 0) ) { break; }
                 if (
                     fargs[0] === 64 && fargs[3] !== selector ||
                     fargs[0] === 65 && JSON.parse(fargs[3]).raw !== selector