diff --git a/include/types/sample.h b/include/types/sample.h
index a5140d6..2dd18e6 100644
--- a/include/types/sample.h
+++ b/include/types/sample.h
@@ -261,7 +261,8 @@
 struct sample_conv {
 	const char *kw;                           /* configuration keyword  */
 	int (*process)(const struct arg *arg_p,
-		       struct sample *smp);       /* process function */
+		       struct sample *smp,
+	               void *private);            /* process function */
 	unsigned int arg_mask;                    /* arguments (ARG*()) */
 	int (*val_args)(struct arg *arg_p,
 	                struct sample_conv *smp_conv,
@@ -269,7 +270,7 @@
 			char **err_msg);          /* argument validation function */
 	unsigned int in_type;                     /* expected input sample type */
 	unsigned int out_type;                    /* output sample type */
-	unsigned int private;                     /* private values. only used by maps */
+	void *private;                            /* private values. only used by maps and Lua */
 };
 
 /* sample conversion expression */
diff --git a/src/map.c b/src/map.c
index a4fd54b..ec760d1 100644
--- a/src/map.c
+++ b/src/map.c
@@ -133,12 +133,12 @@
 	desc->do_free = 1;
 
 	/* Set the match method. */
-	desc->pat.match = pat_match_fcts[conv->private];
-	desc->pat.parse = pat_parse_fcts[conv->private];
-	desc->pat.index = pat_index_fcts[conv->private];
-	desc->pat.delete = pat_delete_fcts[conv->private];
-	desc->pat.prune = pat_prune_fcts[conv->private];
-	desc->pat.expect_type = pat_match_types[conv->private];
+	desc->pat.match = pat_match_fcts[(long)conv->private];
+	desc->pat.parse = pat_parse_fcts[(long)conv->private];
+	desc->pat.index = pat_index_fcts[(long)conv->private];
+	desc->pat.delete = pat_delete_fcts[(long)conv->private];
+	desc->pat.prune = pat_prune_fcts[(long)conv->private];
+	desc->pat.expect_type = pat_match_types[(long)conv->private];
 
 	/* Set the output parse method. */
 	switch (desc->conv->out_type) {
@@ -184,7 +184,7 @@
 	return 1;
 }
 
-static int sample_conv_map(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_map(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct map_descriptor *desc;
 	struct pattern *pat;
@@ -239,36 +239,36 @@
  * The arguments are: <file>[,<default value>]
  */
 static struct sample_conv_kw_list sample_conv_kws = {ILH, {
-	{ "map",         sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_STR,  PAT_MATCH_STR },
-	{ "map_str",     sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_STR,  PAT_MATCH_STR },
-	{ "map_beg",     sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_STR,  PAT_MATCH_BEG },
-	{ "map_sub",     sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_STR,  PAT_MATCH_SUB },
-	{ "map_dir",     sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_STR,  PAT_MATCH_DIR },
-	{ "map_dom",     sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_STR,  PAT_MATCH_DOM },
-	{ "map_end",     sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_STR,  PAT_MATCH_END },
-	{ "map_reg",     sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_STR,  PAT_MATCH_REG },
-	{ "map_int",     sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_UINT, SMP_T_STR,  PAT_MATCH_INT },
-	{ "map_ip",      sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_ADDR, SMP_T_STR,  PAT_MATCH_IP  },
+	{ "map",         sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_STR,  (void *)PAT_MATCH_STR },
+	{ "map_str",     sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_STR,  (void *)PAT_MATCH_STR },
+	{ "map_beg",     sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_STR,  (void *)PAT_MATCH_BEG },
+	{ "map_sub",     sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_STR,  (void *)PAT_MATCH_SUB },
+	{ "map_dir",     sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_STR,  (void *)PAT_MATCH_DIR },
+	{ "map_dom",     sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_STR,  (void *)PAT_MATCH_DOM },
+	{ "map_end",     sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_STR,  (void *)PAT_MATCH_END },
+	{ "map_reg",     sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_STR,  (void *)PAT_MATCH_REG },
+	{ "map_int",     sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_UINT, SMP_T_STR,  (void *)PAT_MATCH_INT },
+	{ "map_ip",      sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_ADDR, SMP_T_STR,  (void *)PAT_MATCH_IP  },
 
-	{ "map_str_int", sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_UINT, PAT_MATCH_STR },
-	{ "map_beg_int", sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_UINT, PAT_MATCH_BEG },
-	{ "map_sub_int", sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_UINT, PAT_MATCH_SUB },
-	{ "map_dir_int", sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_UINT, PAT_MATCH_DIR },
-	{ "map_dom_int", sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_UINT, PAT_MATCH_DOM },
-	{ "map_end_int", sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_UINT, PAT_MATCH_END },
-	{ "map_reg_int", sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_UINT, PAT_MATCH_REG },
-	{ "map_int_int", sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_UINT, SMP_T_UINT, PAT_MATCH_INT },
-	{ "map_ip_int",  sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_ADDR, SMP_T_UINT, PAT_MATCH_IP  },
+	{ "map_str_int", sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_UINT, (void *)PAT_MATCH_STR },
+	{ "map_beg_int", sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_UINT, (void *)PAT_MATCH_BEG },
+	{ "map_sub_int", sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_UINT, (void *)PAT_MATCH_SUB },
+	{ "map_dir_int", sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_UINT, (void *)PAT_MATCH_DIR },
+	{ "map_dom_int", sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_UINT, (void *)PAT_MATCH_DOM },
+	{ "map_end_int", sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_UINT, (void *)PAT_MATCH_END },
+	{ "map_reg_int", sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_UINT, (void *)PAT_MATCH_REG },
+	{ "map_int_int", sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_UINT, SMP_T_UINT, (void *)PAT_MATCH_INT },
+	{ "map_ip_int",  sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_ADDR, SMP_T_UINT, (void *)PAT_MATCH_IP  },
 
-	{ "map_str_ip",  sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_IPV4, PAT_MATCH_STR },
-	{ "map_beg_ip",  sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_IPV4, PAT_MATCH_BEG },
-	{ "map_sub_ip",  sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_IPV4, PAT_MATCH_SUB },
-	{ "map_dir_ip",  sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_IPV4, PAT_MATCH_DIR },
-	{ "map_dom_ip",  sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_IPV4, PAT_MATCH_DOM },
-	{ "map_end_ip",  sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_IPV4, PAT_MATCH_END },
-	{ "map_reg_ip",  sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_IPV4, PAT_MATCH_REG },
-	{ "map_int_ip",  sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_UINT, SMP_T_IPV4, PAT_MATCH_INT },
-	{ "map_ip_ip",   sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_ADDR, SMP_T_IPV4, PAT_MATCH_IP  },
+	{ "map_str_ip",  sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_IPV4, (void *)PAT_MATCH_STR },
+	{ "map_beg_ip",  sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_IPV4, (void *)PAT_MATCH_BEG },
+	{ "map_sub_ip",  sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_IPV4, (void *)PAT_MATCH_SUB },
+	{ "map_dir_ip",  sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_IPV4, (void *)PAT_MATCH_DIR },
+	{ "map_dom_ip",  sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_IPV4, (void *)PAT_MATCH_DOM },
+	{ "map_end_ip",  sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_IPV4, (void *)PAT_MATCH_END },
+	{ "map_reg_ip",  sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_STR,  SMP_T_IPV4, (void *)PAT_MATCH_REG },
+	{ "map_int_ip",  sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_UINT, SMP_T_IPV4, (void *)PAT_MATCH_INT },
+	{ "map_ip_ip",   sample_conv_map, ARG2(1,STR,STR), sample_load_map, SMP_T_ADDR, SMP_T_IPV4, (void *)PAT_MATCH_IP  },
 
 	{ /* END */ },
 }};
diff --git a/src/proto_http.c b/src/proto_http.c
index 4484bcf..3738aa4 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -11377,7 +11377,7 @@
  * adds an optional offset found in args[0] and emits a string representing
  * the date in RFC-1123/5322 format.
  */
-static int sample_conv_http_date(const struct arg *args, struct sample *smp)
+static int sample_conv_http_date(const struct arg *args, struct sample *smp, void *private)
 {
 	const char day[7][4] = { "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun" };
 	const char mon[12][4] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };
@@ -11428,7 +11428,7 @@
 }
 
 /* Arguments: The list of expected value, the number of parts returned and the separator */
-static int sample_conv_q_prefered(const struct arg *args, struct sample *smp)
+static int sample_conv_q_prefered(const struct arg *args, struct sample *smp, void *private)
 {
 	const char *al = smp->data.str.str;
 	const char *end = al + smp->data.str.len;
diff --git a/src/sample.c b/src/sample.c
index 57b2c00..14a7197 100644
--- a/src/sample.c
+++ b/src/sample.c
@@ -967,7 +967,7 @@
 
 		/* OK cast succeeded */
 
-		if (!conv_expr->conv->process(conv_expr->arg_p, p))
+		if (!conv_expr->conv->process(conv_expr->arg_p, p, conv_expr->conv->private))
 			return NULL;
 	}
 	return p;
@@ -1275,7 +1275,7 @@
 /*    These functions set the data type on return.               */
 /*****************************************************************/
 
-static int sample_conv_bin2base64(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_bin2base64(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct chunk *trash = get_trash_chunk();
 	int b64_len;
@@ -1292,7 +1292,7 @@
 	return 1;
 }
 
-static int sample_conv_bin2hex(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_bin2hex(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct chunk *trash = get_trash_chunk();
 	unsigned char c;
@@ -1311,7 +1311,7 @@
 }
 
 /* hashes the binary input into a 32-bit unsigned int */
-static int sample_conv_djb2(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_djb2(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	smp->data.uint = hash_djb2(smp->data.str.str, smp->data.str.len);
 	if (arg_p && arg_p->data.uint)
@@ -1320,7 +1320,7 @@
 	return 1;
 }
 
-static int sample_conv_str2lower(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_str2lower(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	int i;
 
@@ -1337,7 +1337,7 @@
 	return 1;
 }
 
-static int sample_conv_str2upper(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_str2upper(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	int i;
 
@@ -1355,7 +1355,7 @@
 }
 
 /* takes the netmask in arg_p */
-static int sample_conv_ipmask(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_ipmask(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	smp->data.ipv4.s_addr &= arg_p->data.ipv4.s_addr;
 	smp->type = SMP_T_IPV4;
@@ -1366,7 +1366,7 @@
  * adds an optional offset found in args[1] and emits a string representing
  * the local time in the format specified in args[1] using strftime().
  */
-static int sample_conv_ltime(const struct arg *args, struct sample *smp)
+static int sample_conv_ltime(const struct arg *args, struct sample *smp, void *private)
 {
 	struct chunk *temp;
 	time_t curr_date = smp->data.uint;
@@ -1383,7 +1383,7 @@
 }
 
 /* hashes the binary input into a 32-bit unsigned int */
-static int sample_conv_sdbm(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_sdbm(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	smp->data.uint = hash_sdbm(smp->data.str.str, smp->data.str.len);
 	if (arg_p && arg_p->data.uint)
@@ -1396,7 +1396,7 @@
  * adds an optional offset found in args[1] and emits a string representing
  * the UTC date in the format specified in args[1] using strftime().
  */
-static int sample_conv_utime(const struct arg *args, struct sample *smp)
+static int sample_conv_utime(const struct arg *args, struct sample *smp, void *private)
 {
 	struct chunk *temp;
 	time_t curr_date = smp->data.uint;
@@ -1413,7 +1413,7 @@
 }
 
 /* hashes the binary input into a 32-bit unsigned int */
-static int sample_conv_wt6(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_wt6(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	smp->data.uint = hash_wt6(smp->data.str.str, smp->data.str.len);
 	if (arg_p && arg_p->data.uint)
@@ -1423,7 +1423,7 @@
 }
 
 /* hashes the binary input into a 32-bit unsigned int */
-static int sample_conv_crc32(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_crc32(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	smp->data.uint = hash_crc32(smp->data.str.str, smp->data.str.len);
 	if (arg_p && arg_p->data.uint)
@@ -1503,7 +1503,7 @@
 	return 0;
 }
 
-static int sample_conv_json(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_json(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct chunk *temp;
 	char _str[7]; /* \u + 4 hex digit + null char for sprintf. */
@@ -1617,7 +1617,7 @@
 /* This sample function is designed to extract some bytes from an input buffer.
  * First arg is the offset.
  * Optional second arg is the length to truncate */
-static int sample_conv_bytes(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_bytes(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	if (smp->data.str.len <= arg_p[0].data.uint) {
 		smp->data.str.len = 0;
@@ -1674,7 +1674,7 @@
  * First arg is the index of the field (start at 1)
  * Second arg is a char list of separators (type string)
  */
-static int sample_conv_field(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_field(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	unsigned int field;
 	char *start, *end;
@@ -1725,7 +1725,7 @@
  * First arg is the index of the word (start at 1)
  * Second arg is a char list of words separators (type string)
  */
-static int sample_conv_word(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_word(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	unsigned int word;
 	char *start, *end;
@@ -1819,7 +1819,7 @@
  * location until nothing matches anymore. First arg is the regex to apply to
  * the input string, second arg is the replacement expression.
  */
-static int sample_conv_regsub(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_regsub(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	char *start, *end;
 	struct my_regex *reg = arg_p[0].data.reg;
@@ -1891,7 +1891,7 @@
 /* Takes a UINT on input, applies a binary twos complement and returns the UINT
  * result.
  */
-static int sample_conv_binary_cpl(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_binary_cpl(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	smp->data.uint = ~smp->data.uint;
 	return 1;
@@ -1900,7 +1900,7 @@
 /* Takes a UINT on input, applies a binary "and" with the UINT in arg_p, and
  * returns the UINT result.
  */
-static int sample_conv_binary_and(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_binary_and(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	smp->data.uint &= arg_p->data.uint;
 	return 1;
@@ -1909,7 +1909,7 @@
 /* Takes a UINT on input, applies a binary "or" with the UINT in arg_p, and
  * returns the UINT result.
  */
-static int sample_conv_binary_or(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_binary_or(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	smp->data.uint |= arg_p->data.uint;
 	return 1;
@@ -1918,7 +1918,7 @@
 /* Takes a UINT on input, applies a binary "xor" with the UINT in arg_p, and
  * returns the UINT result.
  */
-static int sample_conv_binary_xor(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_binary_xor(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	smp->data.uint ^= arg_p->data.uint;
 	return 1;
@@ -1927,7 +1927,7 @@
 /* Takes a UINT on input, applies an arithmetic "add" with the UINT in arg_p,
  * and returns the UINT result.
  */
-static int sample_conv_arith_add(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_arith_add(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	smp->data.uint += arg_p->data.uint;
 	return 1;
@@ -1936,7 +1936,7 @@
 /* Takes a UINT on input, applies an arithmetic "sub" with the UINT in arg_p,
  * and returns the UINT result.
  */
-static int sample_conv_arith_sub(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_arith_sub(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	smp->data.uint -= arg_p->data.uint;
 	return 1;
@@ -1945,7 +1945,7 @@
 /* Takes a UINT on input, applies an arithmetic "mul" with the UINT in arg_p,
  * and returns the UINT result.
  */
-static int sample_conv_arith_mul(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_arith_mul(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	smp->data.uint *= arg_p->data.uint;
 	return 1;
@@ -1955,7 +1955,7 @@
  * and returns the UINT result. If arg_p makes the result overflow, then the
  * largest possible quantity is returned.
  */
-static int sample_conv_arith_div(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_arith_div(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	if (arg_p->data.uint)
 		smp->data.uint /= arg_p->data.uint;
@@ -1968,7 +1968,7 @@
  * and returns the UINT result. If arg_p makes the result overflow, then zero
  * is returned.
  */
-static int sample_conv_arith_mod(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_arith_mod(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	if (arg_p->data.uint)
 		smp->data.uint %= arg_p->data.uint;
@@ -1980,7 +1980,7 @@
 /* Takes an UINT on input, applies an arithmetic "neg" and returns the UINT
  * result.
  */
-static int sample_conv_arith_neg(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_arith_neg(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	smp->data.uint = -smp->data.uint;
 	return 1;
@@ -1989,7 +1989,7 @@
 /* Takes a UINT on input, returns true is the value is non-null, otherwise
  * false. The output is a BOOL.
  */
-static int sample_conv_arith_bool(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_arith_bool(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	smp->data.uint = !!smp->data.uint;
 	smp->type = SMP_T_BOOL;
@@ -1999,7 +1999,7 @@
 /* Takes a UINT on input, returns false is the value is non-null, otherwise
  * truee. The output is a BOOL.
  */
-static int sample_conv_arith_not(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_arith_not(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	smp->data.uint = !smp->data.uint;
 	smp->type = SMP_T_BOOL;
@@ -2009,7 +2009,7 @@
 /* Takes a UINT on input, returns true is the value is odd, otherwise false.
  * The output is a BOOL.
  */
-static int sample_conv_arith_odd(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_arith_odd(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	smp->data.uint = smp->data.uint & 1;
 	smp->type = SMP_T_BOOL;
@@ -2019,7 +2019,7 @@
 /* Takes a UINT on input, returns true is the value is even, otherwise false.
  * The output is a BOOL.
  */
-static int sample_conv_arith_even(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_arith_even(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	smp->data.uint = !(smp->data.uint & 1);
 	smp->type = SMP_T_BOOL;
diff --git a/src/stick_table.c b/src/stick_table.c
index 32fd60a..9fe0b86 100644
--- a/src/stick_table.c
+++ b/src/stick_table.c
@@ -809,7 +809,7 @@
  * the table's type. This is a double conversion, but in the future we might
  * support automatic input types to perform the cast on the fly.
  */
-static int sample_conv_in_table(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_in_table(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct stktable *t;
 	struct stktable_key *key;
@@ -835,7 +835,7 @@
  * be easily performed. If the inspected parameter is not stored in the table,
  * <not found> is returned.
  */
-static int sample_conv_table_bytes_in_rate(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_table_bytes_in_rate(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct stktable *t;
 	struct stktable_key *key;
@@ -871,7 +871,7 @@
  * be easily performed. If the inspected parameter is not stored in the table,
  * <not found> is returned.
  */
-static int sample_conv_table_conn_cnt(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_table_conn_cnt(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct stktable *t;
 	struct stktable_key *key;
@@ -906,7 +906,7 @@
  * can be easily performed. If the inspected parameter is not stored in the
  * table, <not found> is returned.
  */
-static int sample_conv_table_conn_cur(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_table_conn_cur(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct stktable *t;
 	struct stktable_key *key;
@@ -941,7 +941,7 @@
  * be easily performed. If the inspected parameter is not stored in the table,
  * <not found> is returned.
  */
-static int sample_conv_table_conn_rate(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_table_conn_rate(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct stktable *t;
 	struct stktable_key *key;
@@ -977,7 +977,7 @@
  * be easily performed. If the inspected parameter is not stored in the table,
  * <not found> is returned.
  */
-static int sample_conv_table_bytes_out_rate(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_table_bytes_out_rate(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct stktable *t;
 	struct stktable_key *key;
@@ -1013,7 +1013,7 @@
  * be easily performed. If the inspected parameter is not stored in the table,
  * <not found> is returned.
  */
-static int sample_conv_table_gpc0(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_table_gpc0(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct stktable *t;
 	struct stktable_key *key;
@@ -1048,7 +1048,7 @@
  * be easily performed. If the inspected parameter is not stored in the table,
  * <not found> is returned.
  */
-static int sample_conv_table_gpc0_rate(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_table_gpc0_rate(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct stktable *t;
 	struct stktable_key *key;
@@ -1084,7 +1084,7 @@
  * comparisons can be easily performed. If the inspected parameter is not stored
  * in the table, <not found> is returned.
  */
-static int sample_conv_table_http_err_cnt(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_table_http_err_cnt(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct stktable *t;
 	struct stktable_key *key;
@@ -1119,7 +1119,7 @@
  * be easily performed. If the inspected parameter is not stored in the table,
  * <not found> is returned.
  */
-static int sample_conv_table_http_err_rate(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_table_http_err_rate(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct stktable *t;
 	struct stktable_key *key;
@@ -1155,7 +1155,7 @@
  * can be easily performed. If the inspected parameter is not stored in the
  * table, <not found> is returned.
  */
-static int sample_conv_table_http_req_cnt(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_table_http_req_cnt(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct stktable *t;
 	struct stktable_key *key;
@@ -1190,7 +1190,7 @@
  * performed. If the inspected parameter is not stored in the table, <not found>
  * is returned.
  */
-static int sample_conv_table_http_req_rate(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_table_http_req_rate(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct stktable *t;
 	struct stktable_key *key;
@@ -1226,7 +1226,7 @@
  * be easily performed. If the inspected parameter is not stored in the table,
  * <not found> is returned.
  */
-static int sample_conv_table_kbytes_in(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_table_kbytes_in(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct stktable *t;
 	struct stktable_key *key;
@@ -1261,7 +1261,7 @@
  * be easily performed. If the inspected parameter is not stored in the table,
  * <not found> is returned.
  */
-static int sample_conv_table_kbytes_out(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_table_kbytes_out(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct stktable *t;
 	struct stktable_key *key;
@@ -1296,7 +1296,7 @@
  * easily performed. If the inspected parameter is not stored in the table,
  * <not found> is returned.
  */
-static int sample_conv_table_server_id(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_table_server_id(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct stktable *t;
 	struct stktable_key *key;
@@ -1331,7 +1331,7 @@
  * can be easily performed. If the inspected parameter is not stored in the
  * table, <not found> is returned.
  */
-static int sample_conv_table_sess_cnt(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_table_sess_cnt(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct stktable *t;
 	struct stktable_key *key;
@@ -1366,7 +1366,7 @@
  * performed. If the inspected parameter is not stored in the table, <not found>
  * is returned.
  */
-static int sample_conv_table_sess_rate(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_table_sess_rate(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct stktable *t;
 	struct stktable_key *key;
@@ -1402,7 +1402,7 @@
  * comparisons can be easily performed. If the inspected parameter is not
  * stored in the table, <not found> is returned.
  */
-static int sample_conv_table_trackers(const struct arg *arg_p, struct sample *smp)
+static int sample_conv_table_trackers(const struct arg *arg_p, struct sample *smp, void *private)
 {
 	struct stktable *t;
 	struct stktable_key *key;