Index: /applications/viewer/jmapviewer/src/org/openstreetmap/gui/jmapviewer/OsmFileCacheTileLoader.java
===================================================================
--- /applications/viewer/jmapviewer/src/org/openstreetmap/gui/jmapviewer/OsmFileCacheTileLoader.java	(revision 24827)
+++ /applications/viewer/jmapviewer/src/org/openstreetmap/gui/jmapviewer/OsmFileCacheTileLoader.java	(revision 24828)
@@ -128,5 +128,5 @@
                 tile.loading = true;
             }
-            tileCacheDir = new File(cacheDirBase, source.getName());
+            tileCacheDir = new File(cacheDirBase, source.getName().replaceAll("[\\\\/:*?\"<>|]", "_"));
             if (!tileCacheDir.exists()) {
                 tileCacheDir.mkdirs();