Index: trunk/test/unit/org/openstreetmap/josm/data/validation/tests/TagCheckerTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/data/validation/tests/TagCheckerTest.java	(revision 17474)
+++ trunk/test/unit/org/openstreetmap/josm/data/validation/tests/TagCheckerTest.java	(revision 17477)
@@ -374,3 +374,12 @@
         assertEquals(0, errors.size());
     }
+
+    /**
+     * Non-regression test for <a href="https://josm.openstreetmap.de/ticket/20437">Bug #20437</a>.
+     */
+    @Test
+    void testTicket20437() {
+        assertFalse(TagChecker.containsUnusualUnicodeCharacter("name:kbp", "Wasɩŋtɔŋ"));
+        assertFalse(TagChecker.containsUnusualUnicodeCharacter("name:kbp", "Kalɩfɔrnii"));
+    }
 }