diff --git a/lib/hcl-prv.h b/lib/hcl-prv.h
index 1d91fde..79179c2 100644
--- a/lib/hcl-prv.h
+++ b/lib/hcl-prv.h
@@ -1063,6 +1063,11 @@ int hcl_logfmtst (
 	hcl_ooi_t nargs
 );
 
+int hcl_sprintfmtst (
+	hcl_t*    hcl,
+	hcl_ooi_t nargs
+);
+
 #if defined(__cplusplus)
 }
 #endif
diff --git a/lib/hcl.c b/lib/hcl.c
index 24bde46..ce8e81c 100644
--- a/lib/hcl.c
+++ b/lib/hcl.c
@@ -276,6 +276,14 @@ void hcl_fini (hcl_t* hcl)
 		hcl->inttostr.t.ptr = HCL_NULL;
 		hcl->inttostr.t.capa = 0;
 	}
+
+	if (hcl->sprintf.xbuf.ptr)
+	{
+		hcl_freemem (hcl, hcl->sprintf.xbuf.ptr);
+		hcl->sprintf.xbuf.ptr = HCL_NULL;
+		hcl->sprintf.xbuf.capa = 0;
+		hcl->sprintf.xbuf.len = 0;
+	}
 }
 
 void hcl_clear (hcl_t* hcl, int flags)
diff --git a/lib/hcl.h b/lib/hcl.h
index dbde917..385b80b 100644
--- a/lib/hcl.h
+++ b/lib/hcl.h
@@ -1082,6 +1082,16 @@ struct hcl_t
 	} inttostr;
 	/* == END BIGINT CONVERSION == */
 
+	struct
+	{
+		struct
+		{
+			hcl_ooch_t* ptr;
+			hcl_oow_t capa;
+			hcl_oow_t len;
+		} xbuf; /* buffer to support sprintf */
+	} sprintf;
+
 	hcl_sbuf_t sbuf[64];
 
 	struct
diff --git a/lib/logfmt.c b/lib/logfmt.c
index 3ddbe4b..c3ddbcc 100644
--- a/lib/logfmt.c
+++ b/lib/logfmt.c
@@ -532,7 +532,7 @@ static hcl_ooi_t __prbfmtv (hcl_t* hcl, int mask, const hcl_bch_t* fmt, ...)
 	va_list ap;
 	hcl_fmtout_t fo;
 
-	fo.mask = 0; /* not used */
+	fo.mask = mask;
 	fo.putch = put_prch;
 	fo.putcs = put_prcs;
 
@@ -549,7 +549,7 @@ hcl_ooi_t hcl_proutbfmt (hcl_t* hcl, int mask, const hcl_bch_t* fmt, ...)
 	va_list ap;
 	hcl_fmtout_t fo;
 
-	fo.mask = 0; /* not used */
+	fo.mask = mask;
 	fo.putch = put_prch;
 	fo.putcs = put_prcs;
 
@@ -566,7 +566,7 @@ hcl_ooi_t hcl_proutufmt (hcl_t* hcl, int mask, const hcl_uch_t* fmt, ...)
 	va_list ap;
 	hcl_fmtout_t fo;
 
-	fo.mask = 0; /* not used */
+	fo.mask = mask;
 	fo.putch = put_prch;
 	fo.putcs = put_prcs;
 
@@ -634,7 +634,7 @@ static hcl_ooi_t __errbfmtv (hcl_t* hcl, int mask, const hcl_bch_t* fmt, ...)
 	va_list ap;
 	hcl_fmtout_t fo;
 
-	fo.mask = 0; /* not used */
+	fo.mask = mask;
 	fo.putch = put_errch;
 	fo.putcs = put_errcs;
 
@@ -1146,3 +1146,134 @@ int hcl_logfmtst (hcl_t* hcl, hcl_ooi_t nargs)
 	fo.putcs = put_oocs;
 	return print_formatted(hcl, nargs, &fo, hcl_logbfmt);
 }
+
+
+
+
+
+
+/* -------------------------------------------------------------------------- 
+ * SUPPORT FOR THE BUILTIN PRINTF PRIMITIVE FUNCTION
+ * -------------------------------------------------------------------------- */
+
+static int put_sprch (hcl_t* hcl, int mask, hcl_ooch_t ch, hcl_oow_t len)
+{
+	if (hcl->sprintf.xbuf.len >= hcl->sprintf.xbuf.capa)
+	{
+		hcl_ooch_t* tmp;
+		hcl_oow_t newcapa;
+
+		newcapa = hcl->sprintf.xbuf.len + len + 1;
+		newcapa = HCL_ALIGN_POW2(newcapa, 256);
+
+		tmp = (hcl_ooch_t*)hcl_reallocmem(hcl, hcl->sprintf.xbuf.ptr, newcapa * HCL_SIZEOF(*tmp));
+		if (!tmp) return -1;
+
+		hcl->sprintf.xbuf.ptr = tmp;
+		hcl->sprintf.xbuf.capa = newcapa;
+	}
+
+	while (len > 0)
+	{
+		--len;
+		hcl->sprintf.xbuf.ptr[hcl->sprintf.xbuf.len++] = ch;
+	}
+
+	return 1; /* success */
+}
+
+static int put_sprcs (hcl_t* hcl, int mask, const hcl_ooch_t* ptr, hcl_oow_t len)
+{
+	if (hcl->sprintf.xbuf.len >= hcl->sprintf.xbuf.capa)
+	{
+		hcl_ooch_t* tmp;
+		hcl_oow_t newcapa;
+
+		newcapa = hcl->sprintf.xbuf.len + len + 1;
+		newcapa = HCL_ALIGN_POW2(newcapa, 256);
+
+		tmp = (hcl_ooch_t*)hcl_reallocmem(hcl, hcl->sprintf.xbuf.ptr, newcapa * HCL_SIZEOF(*tmp));
+		if (!tmp) return -1;
+
+		hcl->sprintf.xbuf.ptr = tmp;
+		hcl->sprintf.xbuf.capa = newcapa;
+	}
+
+	HCL_MEMCPY (&hcl->sprintf.xbuf.ptr[hcl->sprintf.xbuf.len], ptr, len * HCL_SIZEOF(*ptr));
+	hcl->sprintf.xbuf.len += len;
+	return 1; /* success */
+}
+
+static hcl_ooi_t __sprbfmtv (hcl_t* hcl, int mask, const hcl_bch_t* fmt, ...);
+
+static int _sprbfmtv (hcl_t* hcl, const hcl_bch_t* fmt, hcl_fmtout_t* data, va_list ap)
+{
+	return __logbfmtv (hcl, fmt, data, ap, __sprbfmtv);
+}
+
+/*
+static int _sprufmtv (hcl_t* hcl, const hcl_uch_t* fmt, hcl_fmtout_t* data, va_list ap)
+{
+	return __logufmtv (hcl, fmt, data, ap, __sprbfmtv);
+}*/
+
+static hcl_ooi_t __sprbfmtv (hcl_t* hcl, int mask, const hcl_bch_t* fmt, ...)
+{
+	va_list ap;
+	hcl_fmtout_t fo;
+
+	fo.mask = mask; /* not used */
+	fo.putch = put_sprch;
+	fo.putcs = put_sprcs;
+
+	va_start (ap, fmt);
+	_sprbfmtv (hcl, fmt, &fo, ap);
+	va_end (ap);
+
+	return fo.count;
+}
+
+hcl_ooi_t hcl_sproutbfmt (hcl_t* hcl, int mask, const hcl_bch_t* fmt, ...)
+{
+	int x;
+	va_list ap;
+	hcl_fmtout_t fo;
+
+	fo.mask = mask;
+	fo.putch = put_sprch;
+	fo.putcs = put_sprcs;
+
+	va_start (ap, fmt);
+	x = _sprbfmtv (hcl, fmt, &fo, ap);
+	va_end (ap);
+
+	return (x <= -1)? -1: fo.count;
+}
+
+/*
+hcl_ooi_t hcl_sproutufmt (hcl_t* hcl, int mask, const hcl_uch_t* fmt, ...)
+{
+	int x;
+	va_list ap;
+	hcl_fmtout_t fo;
+
+	fo.mask = mask;
+	fo.putch = put_sprch;
+	fo.putcs = put_sprcs;
+
+	va_start (ap, fmt);
+	x = _sprufmtv (hcl, fmt, &fo, ap);
+	va_end (ap);
+
+	return (x <= -1)? -1: fo.count;
+}*/
+
+int hcl_sprintfmtst (hcl_t* hcl, hcl_ooi_t nargs)
+{
+	hcl_fmtout_t fo;
+	HCL_MEMSET (&fo, 0, HCL_SIZEOF(fo));
+	fo.putch = put_sprch;
+	fo.putcs = put_sprcs;
+	hcl->sprintf.xbuf.len = 0;
+	return print_formatted(hcl, nargs, &fo, hcl_sproutbfmt);
+}
diff --git a/lib/prim.c b/lib/prim.c
index 1b41825..6ce86fa 100644
--- a/lib/prim.c
+++ b/lib/prim.c
@@ -197,6 +197,25 @@ static hcl_pfrc_t pf_printf (hcl_t* hcl, hcl_mod_t* mod, hcl_ooi_t nargs)
 	return HCL_PF_SUCCESS;
 }
 
+static hcl_pfrc_t pf_sprintf (hcl_t* hcl, hcl_mod_t* mod, hcl_ooi_t nargs)
+{
+	if (hcl_sprintfmtst(hcl, nargs) <= -1)
+	{
+		HCL_STACK_SETRETTOERRNUM (hcl, nargs);
+	}
+	else
+	{
+		hcl_oop_t str;
+		str = hcl_makestring (hcl, hcl->sprintf.xbuf.ptr, hcl->sprintf.xbuf.len, 0);
+		if (!str) return HCL_PF_FAILURE;
+
+		HCL_STACK_SETRET (hcl, nargs, str);
+	}
+
+	return HCL_PF_SUCCESS;
+}
+
+
 
 static hcl_pfrc_t pf_gc (hcl_t* hcl, hcl_mod_t* mod, hcl_ooi_t nargs)
 {
@@ -413,6 +432,7 @@ static pf_t builtin_prims[] =
 	{ 0, HCL_TYPE_MAX(hcl_oow_t), pf_log,           3,  { 'l','o','g' } },
 	{ 1, HCL_TYPE_MAX(hcl_oow_t), pf_logf,          4,  { 'l','o','g','f' } },
 	{ 1, HCL_TYPE_MAX(hcl_oow_t), pf_printf,        6,  { 'p','r','i','n','t','f' } },
+	{ 1, HCL_TYPE_MAX(hcl_oow_t), pf_sprintf,       7,  { 's','p','r','i','n','t','f' } },
 
 	{ 0, 0,                       pf_gc,            2,  { 'g','c' } },