--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2011-02-20  Bruno Haible  <bruno@clisp.org>
+
+	wcrtomb: Enhance test.
+	* tests/test-wcrtomb.c (main): Add test against bug with NULL argument.
+
 2011-02-20  Bruno Haible  <bruno@clisp.org>
 
 	mbrtowc: Tiny optimization.

--- a/tests/test-wcrtomb.c
+++ b/tests/test-wcrtomb.c
@@ -105,6 +105,14 @@
         }
   }
 
+  /* Test special calling convention, passing a NULL pointer.  */
+  {
+    ret = wcrtomb (NULL, '\0', NULL);
+    ASSERT (ret == 1);
+    ret = wcrtomb (NULL, btowc ('x'), NULL);
+    ASSERT (ret == 1);
+  }
+
   if (argc > 1)
     switch (argv[1][0])
       {