diff --git a/source/de/anomic/crawler/Balancer.java b/source/de/anomic/crawler/Balancer.java
index cbf9fb748..f0145314e 100644
--- a/source/de/anomic/crawler/Balancer.java
+++ b/source/de/anomic/crawler/Balancer.java
@@ -176,7 +176,7 @@ public class Balancer {
     
     public synchronized CrawlEntry get(String urlhash) throws IOException {
         assert urlhash != null;
-        if (urlFileIndex == null) return null; // case occurrs during shutdown
+        if (urlFileIndex == null) return null; // case occurs during shutdown
         kelondroRow.Entry entry = urlFileIndex.get(urlhash.getBytes());
         if (entry == null) return null;
         return new CrawlEntry(entry);
diff --git a/source/de/anomic/crawler/CrawlQueues.java b/source/de/anomic/crawler/CrawlQueues.java
index 105cdf5c6..f871fd874 100644
--- a/source/de/anomic/crawler/CrawlQueues.java
+++ b/source/de/anomic/crawler/CrawlQueues.java
@@ -101,6 +101,7 @@ public class CrawlQueues {
     
     public yacyURL getURL(String urlhash) {
         assert urlhash != null;
+        if (urlhash == null || urlhash.length() == 0) return null;
         CrawlEntry ne = noticeURL.get(urlhash);
         if (ne != null) return ne.url();
         ZURL.Entry ee = delegatedURL.getEntry(urlhash);
diff --git a/source/de/anomic/kelondro/kelondroRowSet.java b/source/de/anomic/kelondro/kelondroRowSet.java
index 25103ee88..38363f0a4 100644
--- a/source/de/anomic/kelondro/kelondroRowSet.java
+++ b/source/de/anomic/kelondro/kelondroRowSet.java
@@ -186,6 +186,7 @@ public class kelondroRowSet extends kelondroRowCollection implements kelondroInd
         
         if ((this.rowdef.objectOrder != null) && (this.rowdef.objectOrder instanceof kelondroBase64Order) && (this.sortBound > 4000)) {
             // first try to find in sorted area
+            assert this.rowdef.objectOrder.wellformed(a, astart, alength) : "not wellformed: " + new String(a, astart, alength);
             final byte[] compiledPivot = compilePivot(a, astart, alength);
             int p = binarySearchCompiledPivot(compiledPivot);
             if (p >= 0) return p;