diff --git a/openbis/source/java/ch/systemsx/cisd/openbis/plugin/query/server/QueryServer.java b/openbis/source/java/ch/systemsx/cisd/openbis/plugin/query/server/QueryServer.java
index 30a60e2c67d800ef34e19cb25bda54e2a138d4bf..c1e186fd1affaa1c294726745e1e2f92855ca014 100644
--- a/openbis/source/java/ch/systemsx/cisd/openbis/plugin/query/server/QueryServer.java
+++ b/openbis/source/java/ch/systemsx/cisd/openbis/plugin/query/server/QueryServer.java
@@ -25,6 +25,7 @@ import java.util.Map;
 import javax.annotation.Resource;
 
 import org.apache.commons.lang.StringEscapeUtils;
+import org.apache.commons.lang.StringUtils;
 import org.springframework.dao.DataAccessException;
 import org.springframework.stereotype.Component;
 
@@ -144,7 +145,7 @@ public class QueryServer extends AbstractServer<IQueryServer> implements IQueryS
                 {
                     final String queryEntityTypeCodePatternOrNull =
                             query.getEntityTypeCodePattern();
-                    if (queryEntityTypeCodePatternOrNull == null
+                    if (StringUtils.isEmpty(queryEntityTypeCodePatternOrNull)
                             || entityTypeCode.matches(queryEntityTypeCodePatternOrNull))
                     {
                         filtered.add(query);