Index: /trunk/test/unit/org/openstreetmap/josm/gui/dialogs/properties/TagEditHelperTest.java
===================================================================
--- /trunk/test/unit/org/openstreetmap/josm/gui/dialogs/properties/TagEditHelperTest.java	(revision 15926)
+++ /trunk/test/unit/org/openstreetmap/josm/gui/dialogs/properties/TagEditHelperTest.java	(revision 15927)
@@ -6,4 +6,5 @@
 import static org.junit.Assert.assertNotNull;
 
+import java.awt.GraphicsEnvironment;
 import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
@@ -35,4 +36,5 @@
 import org.openstreetmap.josm.gui.mappaint.mapcss.MapCSSStyleSource;
 import org.openstreetmap.josm.testutils.JOSMTestRules;
+import org.openstreetmap.josm.testutils.mockers.WindowMocker;
 
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
@@ -97,4 +99,8 @@
     public void testTicket18764() throws NoSuchMethodException, SecurityException, IllegalAccessException,
             IllegalArgumentException, InvocationTargetException, NoSuchFieldException {
+        TestUtils.assumeWorkingJMockit();
+        if (GraphicsEnvironment.isHeadless()) {
+            new WindowMocker();
+        }
         MapCSSStyleSource css = new MapCSSStyleSource(
                 "*[building] ⧉ *[highway] { text: tr(\"Building crossing highway\"); }");