Index: trunk/src/org/openstreetmap/josm/data/validation/OsmValidator.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/validation/OsmValidator.java	(revision 18648)
+++ trunk/src/org/openstreetmap/josm/data/validation/OsmValidator.java	(revision 18649)
@@ -467,5 +467,5 @@
                 if (tr("Ignore list").equals(description))
                     description = "";
-                if (!key.matches("^[0-9]+(_.*|$)")) {
+                if (!key.matches("^-?[0-9]+(_.*|$)")) {
                     description = key;
                     key = "";
@@ -480,5 +480,5 @@
                     // single element
                     entry = key + ":" + item;
-                } else if (item.matches("^[0-9]+(_.*|)$")) {
+                } else if (item.matches("^-?[0-9]+(_.*|)$")) {
                     // no element ids
                     entry = item;