Index: /trunk/src/org/openstreetmap/josm/gui/mappaint/mapcss/ConditionFactory.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/mappaint/mapcss/ConditionFactory.java	(revision 16286)
+++ /trunk/src/org/openstreetmap/josm/gui/mappaint/mapcss/ConditionFactory.java	(revision 16287)
@@ -360,5 +360,5 @@
          */
         public KeyValueRegexpCondition(String k, String v, Op op, boolean considerValAsKey) {
-            super(k, "" /* v is not needed */, op, considerValAsKey);
+            super(k, v, op, considerValAsKey); /* value is needed in validator messages */
             CheckParameterUtil.ensureThat(!considerValAsKey, "considerValAsKey is not supported");
             CheckParameterUtil.ensureThat(SUPPORTED_OPS.contains(op), "Op must be REGEX or NREGEX");