Index: trunk/src/org/openstreetmap/josm/gui/layer/geoimage/CorrelateGpxWithImages.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/layer/geoimage/CorrelateGpxWithImages.java	(revision 5221)
+++ trunk/src/org/openstreetmap/josm/gui/layer/geoimage/CorrelateGpxWithImages.java	(revision 5222)
@@ -717,8 +717,10 @@
                 case CANCEL:
                 {
-                    for (ImageEntry ie : yLayer.data) {
-                        ie.tmp = null;
+                    if (yLayer != null) {
+                        for (ImageEntry ie : yLayer.data) {
+                            ie.tmp = null;
+                        }
+                        yLayer.updateBufferAndRepaint();
                     }
-                    yLayer.updateBufferAndRepaint();
                     break;
                 }