diff --git a/source/de/anomic/plasma/parser/Word.java b/source/de/anomic/plasma/parser/Word.java
index fb2425374..fd65fd07a 100644
--- a/source/de/anomic/plasma/parser/Word.java
+++ b/source/de/anomic/plasma/parser/Word.java
@@ -82,11 +82,15 @@ public class Word {
 
     // create a word hash
     public static final byte[] word2hash(final String word) {
-        byte[] h = hashCache.get(word);
+    	byte[] h = hashCache.get(word);
         if (h != null) return h;
-        h = Base64Order.enhancedCoder.encodeSubstring(Digest.encodeMD5Raw(word.toLowerCase(Locale.ENGLISH)), yacySeedDB.commonHashLength);
-        assert h[2] != '@';
-        hashCache.put(word, h); // prevent expensive MD5 computation and encoding
+        synchronized(hashCache) {
+        	h = hashCache.get(word); // we must test that again because another thread may have written the value in between
+            if (h != null) return h;
+            h = Base64Order.enhancedCoder.encodeSubstring(Digest.encodeMD5Raw(word.toLowerCase(Locale.ENGLISH)), yacySeedDB.commonHashLength);
+            assert h[2] != '@';
+            hashCache.put(word, h); // prevent expensive MD5 computation and encoding
+        }
         return h;
     }
     
diff --git a/source/de/anomic/plasma/plasmaSearchRankingProcess.java b/source/de/anomic/plasma/plasmaSearchRankingProcess.java
index fbb5891b1..de9ca3836 100644
--- a/source/de/anomic/plasma/plasmaSearchRankingProcess.java
+++ b/source/de/anomic/plasma/plasmaSearchRankingProcess.java
@@ -301,7 +301,7 @@ public final class plasmaSearchRankingProcess {
     }
     
     public URLMetadataRow bestURL(final boolean skipDoubleDom) {
-        // returns from the current RWI list the best URL entry and removed this entry from the list
+        // returns from the current RWI list the best URL entry and removes this entry from the list
         while ((stack.size() > 0) || (size() > 0)) {
                 if (((stack.size() == 0) && (size() == 0))) break;
                 final SortStack<WordReferenceVars>.stackElement obrwi = bestRWI(skipDoubleDom);
@@ -309,8 +309,12 @@ public final class plasmaSearchRankingProcess {
                 final URLMetadataRow u = wordIndex.metadata().load(obrwi.element.metadataHash(), obrwi.element, obrwi.weight.longValue());
                 if (u != null) {
                     final URLMetadataRow.Components metadata = u.metadata();
-                    if (metadata.url() != null) this.handover.put(u.hash(), metadata.url().toNormalform(true, false)); // remember that we handed over this url
-                    return u;
+                    if (metadata.url() != null) {
+                    	String urlstring = metadata.url().toNormalform(true, true);
+                    	if (urlstring == null || !urlstring.matches(query.urlMask)) continue;                    
+                        this.handover.put(u.hash(), metadata.url().toNormalform(true, false)); // remember that we handed over this url
+                        return u;
+                    }
                 }
                 misses.add(obrwi.element.metadataHash());
         }