Index: trunk/src/org/openstreetmap/josm/tools/HiDPISupport.java
===================================================================
--- trunk/src/org/openstreetmap/josm/tools/HiDPISupport.java	(revision 12723)
+++ trunk/src/org/openstreetmap/josm/tools/HiDPISupport.java	(revision 12724)
@@ -140,4 +140,6 @@
      */
     private static double getHiDPIScale() {
+        if (GraphicsEnvironment.isHeadless())
+            return 1.0;
         GraphicsConfiguration gc = GraphicsEnvironment
                 .getLocalGraphicsEnvironment()