Index: trunk/src/org/openstreetmap/josm/data/validation/tests/SimilarNamedWays.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/validation/tests/SimilarNamedWays.java	(revision 15078)
+++ trunk/src/org/openstreetmap/josm/data/validation/tests/SimilarNamedWays.java	(revision 15079)
@@ -245,5 +245,7 @@
             for (int i = 0; i < words.length; i++) {
                 String word = words[i];
-                part = name.substring(start, start + word.length());
+                if (start + word.length() <= name.length()) {
+                    part = name.substring(start, start + word.length());
+                }
                 if (word.equalsIgnoreCase(part)) {
                     break;