diff --git a/hawk/lib/mod-hawk.c b/hawk/lib/mod-hawk.c
index 98f17d77..9e71e904 100644
--- a/hawk/lib/mod-hawk.c
+++ b/hawk/lib/mod-hawk.c
@@ -147,6 +147,30 @@ static int fnc_function_exists (hawk_rtx_t* rtx, const hawk_fnc_info_t* fi)
 	hawk_rtx_setretval (rtx, hawk_rtx_makeintval(rtx, rx));
 	return 0;
 }
+/* -------------------------------------------------------------------------- */
+
+static int fnc_cmgr_exists (hawk_rtx_t* rtx, const hawk_fnc_info_t*  fi)
+{
+	hawk_val_t* a0;
+	hawk_ooch_t* str;
+	hawk_oow_t len;
+	int rx;
+
+	a0 = hawk_rtx_getarg(rtx, 0);
+	str = hawk_rtx_getvaloocstr(rtx, a0, &len);
+	if (HAWK_UNLIKELY(!str))
+	{
+		rx = 0;
+	}
+	else
+	{
+		rx = (hawk_get_cmgr_by_name(str) != HAWK_NULL);
+		hawk_rtx_freevaloocstr (rtx, a0, str);
+	}
+
+	hawk_rtx_setretval (rtx, hawk_rtx_makeintval(rtx, rx));
+	return 0;
+}
 
 /* -------------------------------------------------------------------------- */
 
@@ -364,6 +388,7 @@ static int fnc_typename (hawk_rtx_t* rtx, const hawk_fnc_info_t* fi)
 	hawk_rtx_setretval (rtx, r);
 	return 0;
 }
+
 /* -------------------------------------------------------------------------- */
 #if 0
 static int pack_data (hawk_rtx_t* rtx, const hawk_oocs_t* fmt, const hawk_fnc_info_t* fi)
@@ -378,7 +403,7 @@ static int pack_data (hawk_rtx_t* rtx, const hawk_oocs_t* fmt, const hawk_fnc_in
 	bp = buf;
 
 	fmte = fmt->ptr + fmt->len;
-	for (fmtp = fmt,ptr; fmtp < fmte; fmtp++) 
+	for (fmtp = fmt->ptr; fmtp < fmte; fmtp++) 
 	{
 		switch (*fmtp) 
 		{
@@ -581,6 +606,7 @@ static fnctab_t fnctab[] =
 	/* keep this table sorted for binary search in query(). */
 	{ HAWK_T("array"),            { { 0, A_MAX,  HAWK_NULL    },  fnc_array,                 0 } },
 	{ HAWK_T("call"),             { { 1, A_MAX, HAWK_T("vR")  },  fnc_call,                  0 } },
+	{ HAWK_T("cmgr_exists"),      { { 1, 1,     HAWK_NULL     },  fnc_cmgr_exists,           0 } },
 	{ HAWK_T("function_exists"),  { { 1, 1,     HAWK_NULL     },  fnc_function_exists,       0 } },
 	{ HAWK_T("gc"),               { { 0, 1,     HAWK_NULL     },  fnc_gc,                    0 } },
 	{ HAWK_T("gcrefs"),           { { 1, 1,     HAWK_NULL     },  fnc_gcrefs,                0 } },
diff --git a/hawk/lib/mod-str.c b/hawk/lib/mod-str.c
index 4a425023..f02f7175 100644
--- a/hawk/lib/mod-str.c
+++ b/hawk/lib/mod-str.c
@@ -540,7 +540,17 @@ static int fnc_tombs (hawk_rtx_t* rtx, const hawk_fnc_info_t* fi)
 	a0 = hawk_rtx_getarg(rtx, 0);
 	switch (HAWK_RTX_GETVALTYPE(rtx, a0))
 	{
+		case HAWK_VAL_BCHR:
+		{
+			/* no conversion, but make it a byte string */
+			hawk_bch_t tmp = HAWK_RTX_GETBCHRFROMVAL(rtx, a0);
+			r = hawk_rtx_makembsvalwithbchars(rtx, &tmp, 1);
+			if (HAWK_UNLIKELY(!r)) return -1;
+			break;
+		}
+		
 		case HAWK_VAL_MBS:
+			/* no conversion */
 			r = a0;
 			break;
 
@@ -551,7 +561,7 @@ static int fnc_tombs (hawk_rtx_t* rtx, const hawk_fnc_info_t* fi)
 			if (HAWK_UNLIKELY(!str.ptr)) return -1;
 			r = hawk_rtx_makembsvalwithbcs(rtx, &str);
 			hawk_rtx_freevalbcstr (rtx, a0, str.ptr);
-			if (!r) return -1;
+			if (HAWK_UNLIKELY(!r)) return -1;
 			break;
 		}
 	}
diff --git a/hawk/lib/utl-str.c b/hawk/lib/utl-str.c
index ed849192..550fb9e0 100644
--- a/hawk/lib/utl-str.c
+++ b/hawk/lib/utl-str.c
@@ -3716,7 +3716,6 @@ hawk_cmgr_t* hawk_get_cmgr_by_id (hawk_cmgr_id_t id)
 	return &builtin_cmgr[id];
 }
 
-
 static struct
 {
 	const hawk_bch_t* name;
diff --git a/hawk/lib/val.c b/hawk/lib/val.c
index 19e41f83..4cc28eec 100644
--- a/hawk/lib/val.c
+++ b/hawk/lib/val.c
@@ -2222,22 +2222,47 @@ hawk_bch_t* hawk_rtx_valtobcstrdupwithcmgr (hawk_rtx_t* rtx, const hawk_val_t* v
 
 	switch (vtype)
 	{
+		case HAWK_VAL_BCHR:
+		{
+			hawk_bch_t tmp = HAWK_RTX_GETBCHRFROMVAL(rtx, v);
+			mbs = hawk_rtx_dupbchars(rtx, &v, 1);
+			if (!mbs) return HAWK_NULL;
+			if (len) *len = 1;
+			break;
+		}
+
 		case HAWK_VAL_MBS:
 			mbs = hawk_rtx_dupbchars(rtx, ((hawk_val_mbs_t*)v)->val.ptr, ((hawk_val_mbs_t*)v)->val.len);
 			if (!mbs) return HAWK_NULL;
 			if (len) *len = ((hawk_val_mbs_t*)v)->val.len;
 			break;
 
+		case HAWK_VAL_CHAR:
 		case HAWK_VAL_STR:
 		{
+			const hawk_ooch_t* ptr;
+			hawk_oow_t slen;
+			hawk_ooch_t tmp;
+
+			if (vtype == HAWK_VAL_CHAR)
+			{
+				tmp = HAWK_RTX_GETCHARFROMVAL(rtx, v);
+				ptr = &tmp;
+				slen = 1;
+			}
+			else
+			{
+				ptr = ((hawk_val_str_t*)v)->val.ptr;
+				slen = ((hawk_val_str_t*)v)->val.len;
+			}
 		#if defined(HAWK_OOCH_IS_BCH)
-			mbs = hawk_rtx_dupbchars(rtx, ((hawk_val_str_t*)v)->val.ptr, ((hawk_val_str_t*)v)->val.len);
+			mbs = hawk_rtx_dupbchars(rtx, (ptr, slen);
 			if (!mbs) return HAWK_NULL;
-			if (len) *len = ((hawk_val_str_t*)v)->val.len;
+			if (len) *len = slen;
 		#else
 			hawk_oow_t mbslen, wcslen;
-			wcslen = ((hawk_val_str_t*)v)->val.len;
-			mbs = hawk_rtx_duputobcharswithcmgr(rtx, ((hawk_val_str_t*)v)->val.ptr, wcslen, &mbslen, cmgr);
+			wcslen = slen;
+			mbs = hawk_rtx_duputobcharswithcmgr(rtx, ptr, wcslen, &mbslen, cmgr);
 			if (!mbs) return HAWK_NULL;
 			if (len) *len = mbslen;
 		#endif
diff --git a/hawk/t/h-002.hawk b/hawk/t/h-002.hawk
index 375f3d92..57536d85 100644
--- a/hawk/t/h-002.hawk
+++ b/hawk/t/h-002.hawk
@@ -378,7 +378,7 @@ function main()
 		ensure (str::substr("☕Q⛄", 4) === "",            1, @SCRIPTNAME, @SCRIPTLINE);
 		ensure (str::substr("☕Q⛄", 1, 2) === "☕Q",         1, @SCRIPTNAME, @SCRIPTLINE);
 		ensure (str::substr("☕Q⛄", 1, 4) === "☕Q⛄",         1, @SCRIPTNAME, @SCRIPTLINE);
-		###ensure (str::substr("☕Q⛄", -1, 1) === "⛄",         1, @SCRIPTNAME, @SCRIPTLINE);
+		###ensure (str::substr("☕Q⛄", -1, 1) === "⛄",         1, @SCRIPTNAME, @SCRIPTLINE); ## not supported yet
 		ensure (str::substr('☕', 1, 4) === "☕",         1, @SCRIPTNAME, @SCRIPTLINE);
 
 		ensure (str::substr(@b"\xAD\xAA\xBB\CC", 2, 2) === @b"\xAA\xBB", 1, @SCRIPTNAME, @SCRIPTLINE);