Index: applications/viewer/jmapviewer/src/org/openstreetmap/gui/jmapviewer/Tile.java
===================================================================
--- applications/viewer/jmapviewer/src/org/openstreetmap/gui/jmapviewer/Tile.java	(revision 31082)
+++ applications/viewer/jmapviewer/src/org/openstreetmap/gui/jmapviewer/Tile.java	(revision 31118)
@@ -49,7 +49,7 @@
     protected BufferedImage image;
     protected String key;
-    protected boolean loaded = false;
-    protected boolean loading = false;
-    protected boolean error = false;
+    protected volatile boolean loaded = false; // field accessed by multiple threads without any monitors, needs to be volatile
+    protected volatile boolean loading = false;
+    protected volatile boolean error = false;
     protected String error_message;