diff --git a/openbis/source/java/ch/systemsx/cisd/openbis/generic/client/web/client/application/ui/grid/ListColumnFilterWidget.java b/openbis/source/java/ch/systemsx/cisd/openbis/generic/client/web/client/application/ui/grid/ListColumnFilterWidget.java
index 49f361cca2989344b89ba9e05524d42e48fb9e19..45567c6a0917a54908cc7d5162a0fc9696ecd9ab 100644
--- a/openbis/source/java/ch/systemsx/cisd/openbis/generic/client/web/client/application/ui/grid/ListColumnFilterWidget.java
+++ b/openbis/source/java/ch/systemsx/cisd/openbis/generic/client/web/client/application/ui/grid/ListColumnFilterWidget.java
@@ -202,7 +202,7 @@ public class ListColumnFilterWidget<T> extends ComboBox<ModelData> implements
         } else if (pattern.equals(EMPTY_VALUE))
         {
             // when EMPTY_VALUE is selected match only empty strings
-            pattern = "^&";
+            pattern = "^$";
         } else if (comboBoxValueSelected)
         {
             // otherwise when combo box value is selected match exact text