diff --git a/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/dto/hibernate/SortableNumberBridgeUtils.java b/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/dto/hibernate/SortableNumberBridgeUtils.java
index 7ebe53b2e5c0c8ad6ca4fe195a58d09d6638a468..a90e542345ebd126c5023f6aea6766ac2a81b280 100644
--- a/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/dto/hibernate/SortableNumberBridgeUtils.java
+++ b/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/dto/hibernate/SortableNumberBridgeUtils.java
@@ -20,7 +20,7 @@ public class SortableNumberBridgeUtils
                 return getNumberForLucene(Double.parseDouble(number));
             } catch (Exception ex2)
             {
-                return number;
+                return "\"" + number + "\"";
             }
         }
     }