diff --git a/moo/kernel/test-001.moo b/moo/kernel/test-001.moo
index eef2b66..e8746fb 100644
--- a/moo/kernel/test-001.moo
+++ b/moo/kernel/test-001.moo
@@ -392,7 +392,6 @@ extend MyObject
 			[ self testBigintDiv: 76733673740671314025981152630586699414203 divisor: 12682136550675277273 count: 1 ],
 			[ self testBigintDiv: 265804060782114895959697138188904455994 divisor: 713053462628379038341886861235 count: 1],
 
-
 			## =========================
 			[ 
 				| k | 
diff --git a/moo/lib/err.c b/moo/lib/err.c
index 38f7aaf..22957d8 100644
--- a/moo/lib/err.c
+++ b/moo/lib/err.c
@@ -215,6 +215,131 @@ void moo_seterrnum (moo_t* moo, moo_errnum_t errnum)
 	moo->errmsg.len = 0; 
 }
 
+
+static int err_bcs (moo_fmtout_t* fmtout, const moo_bch_t* ptr, moo_oow_t len)
+{
+	moo_t* moo = (moo_t*)fmtout->ctx;
+	moo_oow_t max;
+
+	max = MOO_COUNTOF(moo->errmsg.buf) - moo->errmsg.len - 1;
+
+#if defined(MOO_OOCH_IS_UCH)
+	if (max <= 0) return 1;
+	moo_conv_bchars_to_uchars_with_cmgr (ptr, &len, &moo->errmsg.buf[moo->errmsg.len], &max, moo->cmgr, 1);
+	moo->errmsg.len += max;
+#else
+	if (len > max) len = max;
+	if (len <= 0) return 1;
+	MOO_MEMCPY (&moo->errmsg.buf[moo->errmsg.len], ptr, len * MOO_SIZEOF(*ptr));
+	moo->errmsg.len += len;
+#endif
+
+	moo->errmsg.buf[moo->errmsg.len] = '\0';
+
+	return 1; /* success */
+}
+
+static int err_ucs (moo_fmtout_t* fmtout, const moo_uch_t* ptr, moo_oow_t len)
+{
+	moo_t* moo = (moo_t*)fmtout->ctx;
+	moo_oow_t max;
+
+	max = MOO_COUNTOF(moo->errmsg.buf) - moo->errmsg.len - 1;
+
+#if defined(MOO_OOCH_IS_UCH)
+	if (len > max) len = max;
+	if (len <= 0) return 1;
+	MOO_MEMCPY (&moo->errmsg.buf[moo->errmsg.len], ptr, len * MOO_SIZEOF(*ptr));
+	moo->errmsg.len += len;
+#else
+	if (max <= 0) return 1;
+	moo_conv_uchars_to_bchars_with_cmgr (ptr, &len, &moo->errmsg.buf[moo->errmsg.len], &max, moo->cmgr);
+	moo->errmsg.len += max;
+#endif
+	moo->errmsg.buf[moo->errmsg.len] = '\0';
+	return 1; /* success */
+}
+
+void moo_seterrbfmt (moo_t* moo, moo_errnum_t errnum, const moo_bch_t* fmt, ...)
+{
+	va_list ap;
+	moo_fmtout_t fo;
+
+	if (moo->shuterr) return;
+	moo->errmsg.len = 0;
+
+	MOO_MEMSET (&fo, 0, MOO_SIZEOF(fo));
+	fo.putbcs = err_bcs;
+	fo.putucs = err_ucs;
+	fo.putobj = moo_fmt_object_;
+	fo.ctx = moo;
+
+	va_start (ap, fmt);
+	moo_bfmt_outv (&fo, fmt, ap);
+	va_end (ap);
+
+	moo->errnum = errnum;
+}
+
+void moo_seterrufmt (moo_t* moo, moo_errnum_t errnum, const moo_uch_t* fmt, ...)
+{
+	va_list ap;
+	moo_fmtout_t fo;
+
+	if (moo->shuterr) return;
+	moo->errmsg.len = 0;
+
+	MOO_MEMSET (&fo, 0, MOO_SIZEOF(fo));
+	fo.putbcs = err_bcs;
+	fo.putucs = err_ucs;
+	fo.putobj = moo_fmt_object_;
+	fo.ctx = moo;
+
+	va_start (ap, fmt);
+	moo_ufmt_outv (&fo, fmt, ap);
+	va_end (ap);
+
+	moo->errnum = errnum;
+}
+
+
+void moo_seterrbfmtv (moo_t* moo, moo_errnum_t errnum, const moo_bch_t* fmt, va_list ap)
+{
+	moo_fmtout_t fo;
+
+	if (moo->shuterr) return;
+
+	moo->errmsg.len = 0;
+
+	MOO_MEMSET (&fo, 0, MOO_SIZEOF(fo));
+	fo.putbcs = err_bcs;
+	fo.putucs = err_ucs;
+	fo.putobj = moo_fmt_object_;
+	fo.ctx = moo;
+
+	moo_bfmt_outv (&fo, fmt, ap);
+	moo->errnum = errnum;
+}
+
+void moo_seterrufmtv (moo_t* moo, moo_errnum_t errnum, const moo_uch_t* fmt, va_list ap)
+{
+	moo_fmtout_t fo;
+
+	if (moo->shuterr) return;
+
+	moo->errmsg.len = 0;
+
+	MOO_MEMSET (&fo, 0, MOO_SIZEOF(fo));
+	fo.putbcs = err_bcs;
+	fo.putucs = err_ucs;
+	fo.putobj = moo_fmt_object_;
+	fo.ctx = moo;
+
+	moo_ufmt_outv (&fo, fmt, ap);
+	moo->errnum = errnum;
+}
+
+
 void moo_seterrwithsyserr (moo_t* moo, int syserr_type, int syserr_code)
 {
 	moo_errnum_t errnum;
diff --git a/moo/lib/fmt.c b/moo/lib/fmt.c
index c1baeb2..21f8152 100644
--- a/moo/lib/fmt.c
+++ b/moo/lib/fmt.c
@@ -1267,7 +1267,7 @@ int moo_ufmt_outv (moo_fmtout_t* fmtout, const moo_uch_t* fmt, va_list ap)
 	fmt_str = fmtout->fmt_str;
 	fmt_type = fmtout->fmt_type;
 
-	fmtout->fmt_type = MOO_FMTOUT_FMT_TYPE_BCH;
+	fmtout->fmt_type = MOO_FMTOUT_FMT_TYPE_UCH;
 	fmtout->fmt_str = fmt;
 
 	n = fmt_outv(fmtout, ap);
@@ -1325,7 +1325,7 @@ int moo_ufmt_out (moo_fmtout_t* fmtout, const moo_uch_t* fmt, ...)
  * OBJECT OUTPUT
  * -------------------------------------------------------------------------- */
 
-static int print_object (moo_fmtout_t* fmtout, moo_oop_t oop)
+int moo_fmt_object_ (moo_fmtout_t* fmtout, moo_oop_t oop)
 {
 	moo_t* moo = (moo_t*)fmtout->ctx;
 
@@ -1499,11 +1499,11 @@ static int print_object (moo_fmtout_t* fmtout, moo_oop_t oop)
 			i = 0;
 			if (i < MOO_OBJ_GET_SIZE(oop))
 			{
-				if (print_object(fmtout, MOO_OBJ_GET_OOP_VAL(oop, i)) <= -1) return -1;
+				if (moo_fmt_object_(fmtout, MOO_OBJ_GET_OOP_VAL(oop, i)) <= -1) return -1;
 				for (++i; i < MOO_OBJ_GET_SIZE(oop); i++)
 				{
 					if (moo_bfmt_out(fmtout, " ") <= -1) return -1;
-					if (print_object(fmtout, MOO_OBJ_GET_OOP_VAL(oop, i)) <= -1) return -1;
+					if (moo_fmt_object_(fmtout, MOO_OBJ_GET_OOP_VAL(oop, i)) <= -1) return -1;
 				}
 			}
 			if (moo_bfmt_out(fmtout, ")") <= -1) return -1;
@@ -1701,7 +1701,7 @@ moo_ooi_t moo_logbfmt (moo_t* moo, moo_bitmask_t mask, const moo_bch_t* fmt, ...
 	fo.mask = mask;
 	fo.putbcs = log_bcs;
 	fo.putucs = log_ucs;
-	fo.putobj = print_object;
+	fo.putobj = moo_fmt_object_;
 
 	va_start (ap, fmt);
 	x = fmt_outv(&fo, ap);
@@ -1746,7 +1746,7 @@ moo_ooi_t moo_logufmt (moo_t* moo, moo_bitmask_t mask, const moo_uch_t* fmt, ...
 	fo.mask = mask;
 	fo.putbcs = log_bcs;
 	fo.putucs = log_ucs;
-	fo.putobj = print_object;
+	fo.putobj = moo_fmt_object_;
 
 	va_start (ap, fmt);
 	x = fmt_outv(&fo, ap);
diff --git a/moo/lib/fmtout.c b/moo/lib/fmtout.c
index 8636a86..5b3e52f 100644
--- a/moo/lib/fmtout.c
+++ b/moo/lib/fmtout.c
@@ -696,146 +696,6 @@ moo_ooi_t moo_logufmt (moo_t* moo, moo_bitmask_t mask, const moo_uch_t* fmt, ...
 }
 #endif
 
-/* -------------------------------------------------------------------------- 
- * ERROR MESSAGE FORMATTING
- * -------------------------------------------------------------------------- */
-
-static int put_errch (moo_t* moo, moo_bitmask_t mask, moo_ooch_t ch, moo_oow_t len)
-{
-	moo_oow_t max;
-
-	max = MOO_COUNTOF(moo->errmsg.buf) - moo->errmsg.len - 1;
-	if (len > max) len = max;
-
-	if (len <= 0) return 1;
-
-	while (len > 0)
-	{
-		moo->errmsg.buf[moo->errmsg.len++] = ch;
-		len--;
-	}
-	moo->errmsg.buf[moo->errmsg.len] = '\0';
-
-	return 1; /* success */
-}
-
-static int put_errcs (moo_t* moo, moo_bitmask_t mask, const moo_ooch_t* ptr, moo_oow_t len)
-{
-	moo_oow_t max;
-
-	max = MOO_COUNTOF(moo->errmsg.buf) - moo->errmsg.len - 1;
-	if (len > max) len = max;
-
-	if (len <= 0) return 1;
-
-	MOO_MEMCPY (&moo->errmsg.buf[moo->errmsg.len], ptr, len * MOO_SIZEOF(*ptr));
-	moo->errmsg.len += len;
-	moo->errmsg.buf[moo->errmsg.len] = '\0';
-
-	return 1; /* success */
-}
-
-
-static moo_ooi_t __errbfmtv (moo_t* moo, moo_bitmask_t mask, const moo_bch_t* fmt, ...);
-
-static int _errbfmtv (moo_t* moo, const moo_bch_t* fmt, moo_fmtout_data_t* data, va_list ap)
-{
-	return __logbfmtv (moo, fmt, data, ap, __errbfmtv);
-}
-
-static int _errufmtv (moo_t* moo, const moo_uch_t* fmt, moo_fmtout_data_t* data, va_list ap)
-{
-	return __logufmtv (moo, fmt, data, ap, __errbfmtv);
-}
-
-static moo_ooi_t __errbfmtv (moo_t* moo, moo_bitmask_t mask, const moo_bch_t* fmt, ...)
-{
-	va_list ap;
-	moo_fmtout_data_t fo;
-
-	fo.mask = 0; /* not used */
-	fo.putch = put_errch;
-	fo.putcs = put_errcs;
-
-	va_start (ap, fmt);
-	_errbfmtv (moo, fmt, &fo, ap);
-	va_end (ap);
-
-	return fo.count;
-}
-
-void moo_seterrbfmt (moo_t* moo, moo_errnum_t errnum, const moo_bch_t* fmt, ...)
-{
-	va_list ap;
-	moo_fmtout_data_t fo;
-
-	if (moo->shuterr) return;
-	moo->errmsg.len = 0;
-
-	fo.mask = 0; /* not used */
-	fo.putch = put_errch;
-	fo.putcs = put_errcs;
-
-	va_start (ap, fmt);
-	_errbfmtv (moo, fmt, &fo, ap);
-	va_end (ap);
-
-	moo->errnum = errnum;
-}
-
-void moo_seterrufmt (moo_t* moo, moo_errnum_t errnum, const moo_uch_t* fmt, ...)
-{
-	va_list ap;
-	moo_fmtout_data_t fo;
-
-	if (moo->shuterr) return;
-	moo->errmsg.len = 0;
-
-	fo.mask = 0; /* not used */
-	fo.putch = put_errch;
-	fo.putcs = put_errcs;
-
-	va_start (ap, fmt);
-	_errufmtv (moo, fmt, &fo, ap);
-	va_end (ap);
-
-	moo->errnum = errnum;
-}
-
-
-void moo_seterrbfmtv (moo_t* moo, moo_errnum_t errnum, const moo_bch_t* fmt, va_list ap)
-{
-	moo_fmtout_data_t fo;
-
-	if (moo->shuterr) return;
-
-	moo->errmsg.len = 0;
-
-	fo.mask = 0; /* not used */
-	fo.putch = put_errch;
-	fo.putcs = put_errcs;
-
-	_errbfmtv (moo, fmt, &fo, ap);
-	moo->errnum = errnum;
-}
-
-void moo_seterrufmtv (moo_t* moo, moo_errnum_t errnum, const moo_uch_t* fmt, va_list ap)
-{
-	moo_fmtout_data_t fo;
-
-	if (moo->shuterr) return;
-
-	moo->errmsg.len = 0;
-
-	fo.mask = 0; /* not used */
-	fo.putch = put_errch;
-	fo.putcs = put_errcs;
-
-	_errufmtv (moo, fmt, &fo, ap);
-	moo->errnum = errnum;
-}
-
-
 /* -------------------------------------------------------------------------- 
  * SUPPORT FOR FORMATTED OUTPUT TO BE USED BY BUILTIN PRIMITIVE FUNCTIONS
  * -------------------------------------------------------------------------- */
diff --git a/moo/lib/moo-prv.h b/moo/lib/moo-prv.h
index e035c2e..19aaf8b 100644
--- a/moo/lib/moo-prv.h
+++ b/moo/lib/moo-prv.h
@@ -1483,6 +1483,14 @@ moo_oop_t moo_numtostr (
 );
 
 
+/* ========================================================================= */
+/* fmt.c                                                                  */
+/* ========================================================================= */
+int moo_fmt_object_ (
+	moo_fmtout_t* fmtout,
+	moo_oop_t     oop
+);
+
 /* ========================================================================= */
 /* fmtout.c                                                                  */
 /* ========================================================================= */
diff --git a/moo/lib/moo-utl.h b/moo/lib/moo-utl.h
index fbec788..669cb3c 100644
--- a/moo/lib/moo-utl.h
+++ b/moo/lib/moo-utl.h
@@ -596,7 +596,7 @@ moo_oow_t moo_byte_to_bcstr (
 
 /* ------------------------------------------------------------------------- */
 
-MOO_EXPORT int moo_ucwidth (
+MOO_EXPORT int moo_get_ucwidth (
 	moo_uch_t uc
 );
 
diff --git a/moo/lib/std.c b/moo/lib/std.c
index 9f37a12..b51e739 100644
--- a/moo/lib/std.c
+++ b/moo/lib/std.c
@@ -3624,12 +3624,12 @@ static void fini_moo (moo_t* moo)
 	xtn_t* xtn;
 
 	MOO_MEMSET(&vmprim, 0, MOO_SIZEOF(vmprim));
-	if (cfg->large_pages)
+	if (cfg && cfg->large_pages)
 	{
 		vmprim.alloc_heap = alloc_heap;
 		vmprim.free_heap = free_heap;
 	}
-	vmprim.log_write = (cfg->log_write? cfg->log_write: log_write);
+	vmprim.log_write = ((cfg && cfg->log_write)? cfg->log_write: log_write);
 	vmprim.syserrstrb = syserrstrb;
 	vmprim.assertfail = assert_fail;
 	vmprim.dl_startup = dl_startup;
@@ -3646,13 +3646,13 @@ static void fini_moo (moo_t* moo)
 	vmprim.vm_muxwait = vm_muxwait;
 	vmprim.vm_sleep = vm_sleep;
 
-	moo = moo_open(&sys_mmgr, MOO_SIZEOF(xtn_t) + xtnsize, (cfg->cmgr? cfg->cmgr: moo_get_utf8_cmgr()), &vmprim, errinfo);
+	moo = moo_open(&sys_mmgr, MOO_SIZEOF(xtn_t) + xtnsize, ((cfg && cfg->cmgr)? cfg->cmgr: moo_get_utf8_cmgr()), &vmprim, errinfo);
 	if (!moo) return MOO_NULL;
 
 	xtn = GET_XTN(moo);
-	xtn->input_cmgr = cfg->input_cmgr;
+	if (cfg) xtn->input_cmgr = cfg->input_cmgr;
 	if (!xtn->input_cmgr) xtn->input_cmgr = moo_getcmgr(moo);
-	xtn->log_cmgr = cfg->log_cmgr;
+	if (cfg) xtn->log_cmgr = cfg->log_cmgr;
 	if (!xtn->log_cmgr) xtn->log_cmgr = moo_getcmgr(moo);
 
 	chain (moo); /* call chain() before moo_regevtcb() as fini_moo() calls unchain() */
@@ -3677,7 +3677,7 @@ static void fini_moo (moo_t* moo)
 		moo_setoption (moo, MOO_OPTION_LOG_MASK, &bm);
 	}
 
-	if (handle_cfg_options(moo, cfg) <= -1)
+	if (cfg && handle_cfg_options(moo, cfg) <= -1)
 	{
 		if (errinfo) moo_geterrinf (moo, errinfo);
 		moo_close (moo);
diff --git a/moo/lib/utf8.c b/moo/lib/utf8.c
index 1ca1de4..cb16f13 100644
--- a/moo/lib/utf8.c
+++ b/moo/lib/utf8.c
@@ -239,7 +239,7 @@ static int bisearch(moo_uch_t ucs, const struct interval *table, int max)
  * in ISO 10646.
  */
 
-int moo_ucwidth (moo_uch_t uc)
+int moo_get_ucwidth (moo_uch_t uc)
 {
 	/* sorted list of non-overlapping intervals of non-spacing characters */
 	/* generated by "uniset +cat=Me +cat=Mn +cat=Cf -00AD +1160-11FF +200B c" */
diff --git a/moo/t/Makefile.am b/moo/t/Makefile.am
index 912cb4f..4a4300a 100644
--- a/moo/t/Makefile.am
+++ b/moo/t/Makefile.am
@@ -10,9 +10,20 @@ AM_CPPFLAGS = \
 	-I$(includedir)
 
 AM_LDFLAGS = -L$(abs_builddir)/../lib  -L$(libdir)
-LDADD = -lmoo $(PTHREAD_LIBS)
+LDADD = $(PTHREAD_LIBS)
+
+bin_PROGRAMS = t-001 t-002 t-003 t-004
 
-bin_PROGRAMS = t-001 t-002 t-003
 t_001_SOURCES = t-001.c
+
 t_002_SOURCES = t-002.c
+t_002_LDADD = -lmoo $(LDADD)
+t_002_DEPENDENCIES = ../lib/libmoo.la
+
 t_003_SOURCES = t-003.c
+t_003_LDADD = -lmoo $(LDADD)
+t_003_DEPENDENCIES = ../lib/libmoo.la
+
+t_004_SOURCES = t-004.c
+t_004_LDADD = -lmoox $(LDADD)
+t_004_DEPENDENCIES = ../lib/libmoox.la
diff --git a/moo/t/Makefile.in b/moo/t/Makefile.in
index 9b7b1be..7fe368c 100644
--- a/moo/t/Makefile.in
+++ b/moo/t/Makefile.in
@@ -88,7 +88,8 @@ PRE_UNINSTALL = :
 POST_UNINSTALL = :
 build_triplet = @build@
 host_triplet = @host@
-bin_PROGRAMS = t-001$(EXEEXT) t-002$(EXEEXT) t-003$(EXEEXT)
+bin_PROGRAMS = t-001$(EXEEXT) t-002$(EXEEXT) t-003$(EXEEXT) \
+	t-004$(EXEEXT)
 subdir = t
 ACLOCAL_M4 = $(top_srcdir)/aclocal.m4
 am__aclocal_m4_deps = $(top_srcdir)/m4/ax_check_sign.m4 \
@@ -117,12 +118,11 @@ am__v_lt_0 = --silent
 am__v_lt_1 = 
 am_t_002_OBJECTS = t-002.$(OBJEXT)
 t_002_OBJECTS = $(am_t_002_OBJECTS)
-t_002_LDADD = $(LDADD)
-t_002_DEPENDENCIES = $(am__DEPENDENCIES_1)
+am__DEPENDENCIES_2 = $(am__DEPENDENCIES_1)
 am_t_003_OBJECTS = t-003.$(OBJEXT)
 t_003_OBJECTS = $(am_t_003_OBJECTS)
-t_003_LDADD = $(LDADD)
-t_003_DEPENDENCIES = $(am__DEPENDENCIES_1)
+am_t_004_OBJECTS = t-004.$(OBJEXT)
+t_004_OBJECTS = $(am_t_004_OBJECTS)
 AM_V_P = $(am__v_P_@AM_V@)
 am__v_P_ = $(am__v_P_@AM_DEFAULT_V@)
 am__v_P_0 = false
@@ -157,8 +157,10 @@ AM_V_CCLD = $(am__v_CCLD_@AM_V@)
 am__v_CCLD_ = $(am__v_CCLD_@AM_DEFAULT_V@)
 am__v_CCLD_0 = @echo "  CCLD    " $@;
 am__v_CCLD_1 = 
-SOURCES = $(t_001_SOURCES) $(t_002_SOURCES) $(t_003_SOURCES)
-DIST_SOURCES = $(t_001_SOURCES) $(t_002_SOURCES) $(t_003_SOURCES)
+SOURCES = $(t_001_SOURCES) $(t_002_SOURCES) $(t_003_SOURCES) \
+	$(t_004_SOURCES)
+DIST_SOURCES = $(t_001_SOURCES) $(t_002_SOURCES) $(t_003_SOURCES) \
+	$(t_004_SOURCES)
 am__can_run_installinfo = \
   case $$AM_UPDATE_INFO_DIR in \
     n|no|NO) false;; \
@@ -348,10 +350,17 @@ AM_CPPFLAGS = \
 	-I$(includedir)
 
 AM_LDFLAGS = -L$(abs_builddir)/../lib  -L$(libdir)
-LDADD = -lmoo $(PTHREAD_LIBS)
+LDADD = $(PTHREAD_LIBS)
 t_001_SOURCES = t-001.c
 t_002_SOURCES = t-002.c
+t_002_LDADD = -lmoo $(LDADD)
+t_002_DEPENDENCIES = ../lib/libmoo.la
 t_003_SOURCES = t-003.c
+t_003_LDADD = -lmoo $(LDADD)
+t_003_DEPENDENCIES = ../lib/libmoo.la
+t_004_SOURCES = t-004.c
+t_004_LDADD = -lmoox $(LDADD)
+t_004_DEPENDENCIES = ../lib/libmoox.la
 all: all-am
 
 .SUFFIXES:
@@ -447,6 +456,10 @@ t-003$(EXEEXT): $(t_003_OBJECTS) $(t_003_DEPENDENCIES) $(EXTRA_t_003_DEPENDENCIE
 	@rm -f t-003$(EXEEXT)
 	$(AM_V_CCLD)$(LINK) $(t_003_OBJECTS) $(t_003_LDADD) $(LIBS)
 
+t-004$(EXEEXT): $(t_004_OBJECTS) $(t_004_DEPENDENCIES) $(EXTRA_t_004_DEPENDENCIES) 
+	@rm -f t-004$(EXEEXT)
+	$(AM_V_CCLD)$(LINK) $(t_004_OBJECTS) $(t_004_LDADD) $(LIBS)
+
 mostlyclean-compile:
 	-rm -f *.$(OBJEXT)
 
@@ -456,6 +469,7 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/t-001.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/t-002.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/t-003.Po@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/t-004.Po@am__quote@
 
 .c.o:
 @am__fastdepCC_TRUE@	$(AM_V_CC)depbase=`echo $@ | sed 's|[^/]*$$|$(DEPDIR)/&|;s|\.o$$||'`;\
diff --git a/moo/t/t-004.c b/moo/t/t-004.c
new file mode 100644
index 0000000..98ff370
--- /dev/null
+++ b/moo/t/t-004.c
@@ -0,0 +1,37 @@
+#include <moo-std.h>
+#include <moo-utl.h>
+#include <stdio.h>
+#include "t.h"
+
+int main ()
+{
+	moo_t* moo = MOO_NULL;
+	moo_uch_t ufmt1[] = { '%', '0', '5', 'd', ' ', '%', '-', '9', 'h', 's', '\0' };
+	moo_uch_t ufmt2[] = { '%', '0', '5', 'd', ' ', '%', '-', '9', 'h', 's', ' ', '%','O','\0' };
+
+	moo = moo_openstd(0, MOO_NULL, MOO_NULL);
+	if (!moo)
+	{
+		fprintf (stderr, "Unable to open moo\n");
+		return -1;
+	}
+
+	moo_seterrbfmt (moo, MOO_EINVAL, "%d %ld %s %hs", 10, 20L, "moo", "moo");
+	T_ASSERT1 (moo_comp_oocstr_bcstr(moo_geterrmsg(moo), "10 20 moo moo") == 0, "moo seterrbfmt #1");
+	moo_logbfmt (moo, MOO_LOG_STDERR, "[%js]\n", moo_geterrmsg(moo));
+
+	moo_seterrufmt (moo, MOO_EINVAL, ufmt1, 9923, "moo");
+	T_ASSERT1 (moo_comp_oocstr_bcstr(moo_geterrmsg(moo), "09923 moo      ") == 0, "moo seterrufmt #1");
+	moo_logbfmt (moo, MOO_LOG_STDERR, "[%js]\n", moo_geterrmsg(moo));
+
+	moo_seterrufmt (moo, MOO_EINVAL, ufmt2, 9923, "moo", MOO_SMPTR_TO_OOP(0x12345678));
+	T_ASSERT1 (moo_comp_oocstr_bcstr(moo_geterrmsg(moo), "09923 moo       #\\p12345678") == 0, "moo seterrufmt #1");
+	moo_logbfmt (moo, MOO_LOG_STDERR, "[%js]\n", moo_geterrmsg(moo));
+
+	moo_close (moo);
+	return 0;
+
+oops:
+	if (moo) moo_close (moo);
+	return -1;
+}