diff --git a/src/helma/objectmodel/db/DbMapping.java b/src/helma/objectmodel/db/DbMapping.java
index 7173ad04..5d9c311b 100644
--- a/src/helma/objectmodel/db/DbMapping.java
+++ b/src/helma/objectmodel/db/DbMapping.java
@@ -365,7 +365,7 @@ public final class DbMapping implements Updatable {
         }
 
         if (dbSource == null) {
-            throw new SQLException("Datasource is not defined: " + dbSourceName + ".");
+            throw new SQLException("Datasource not defined or unable to load driver: " + dbSourceName + ".");
         }
 
         return dbSource.getConnection();