Index: trunk/src/org/openstreetmap/josm/data/validation/Test.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/validation/Test.java	(revision 8489)
+++ trunk/src/org/openstreetmap/josm/data/validation/Test.java	(revision 8490)
@@ -183,5 +183,6 @@
         progressMonitor = null;
         if (startTime > 0) {
-            long elapsedTime = System.currentTimeMillis() - startTime;
+            // fix #11567 where elapsedTime is < 0
+            long elapsedTime = Math.max(0, System.currentTimeMillis() - startTime);
             Main.debug(tr("Test ''{0}'' completed in {1}", getName(), Utils.getDurationString(elapsedTime)));
         }