Index: lib/matcher.js
===================================================================
--- a/lib/matcher.js
+++ b/lib/matcher.js
@@ -398,17 +398,17 @@
 
     let result = this.resultCache.get(key);
     if (typeof result != "undefined")
       return result;
 
     result = this.matchesAnyInternal(location, typeMask, docDomain,
                                      thirdParty, sitekey, specificOnly);
 
-    if (this.resultCache.size >= CombinedMatcher.maxCacheEntries)
+    if (this.resultCache.size >= this.maxCacheEntries)
       this.resultCache.clear();
 
     this.resultCache.set(key, result);
 
     return result;
   }
 }