Index: trunk/src/org/openstreetmap/josm/gui/mappaint/mapcss/ExpressionFactory.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/mappaint/mapcss/ExpressionFactory.java	(revision 17802)
+++ trunk/src/org/openstreetmap/josm/gui/mappaint/mapcss/ExpressionFactory.java	(revision 17803)
@@ -142,4 +142,9 @@
 
     static {
+        initFactories();
+    }
+
+    @SuppressWarnings("unchecked")
+    private static void initFactories() {
         FACTORY_MAP.put("CRC32_checksum", Factory.of(String.class, Functions::CRC32_checksum));
         FACTORY_MAP.put("JOSM_pref", Factory.ofEnv(String.class, String.class, null, Functions::JOSM_pref));