Index: branch/0.5/src/org/openstreetmap/josm/actions/SaveActionBase.java
===================================================================
--- branch/0.5/src/org/openstreetmap/josm/actions/SaveActionBase.java	(revision 337)
+++ branch/0.5/src/org/openstreetmap/josm/actions/SaveActionBase.java	(revision 338)
@@ -126,5 +126,5 @@
 				}
 				OsmWriter.output(new FileOutputStream(file), new OsmWriter.All(layer.data, false));
-				if (!Main.pref.getBoolean("save.keepbackup"))
+				if (!Main.pref.getBoolean("save.keepbackup") && (tmpFile != null))
 					tmpFile.delete();
 			} else if (ExtensionFileFilter.filters[ExtensionFileFilter.CSV].acceptName(file.getPath())) {