Index: trunk/src/org/openstreetmap/josm/actions/mapmode/DrawAction.java
===================================================================
--- trunk/src/org/openstreetmap/josm/actions/mapmode/DrawAction.java	(revision 12424)
+++ trunk/src/org/openstreetmap/josm/actions/mapmode/DrawAction.java	(revision 12425)
@@ -786,7 +786,9 @@
      */
     private void tryToSetBaseSegmentForAngleSnap() {
-        WaySegment seg = Main.map.mapView.getNearestWaySegment(mousePos, OsmPrimitive::isSelectable);
-        if (seg != null) {
-            snapHelper.setBaseSegment(seg);
+        if (mousePos != null) {
+            WaySegment seg = Main.map.mapView.getNearestWaySegment(mousePos, OsmPrimitive::isSelectable);
+            if (seg != null) {
+                snapHelper.setBaseSegment(seg);
+            }
         }
     }