diff --git a/include/types/sample.h b/include/types/sample.h
index 956e7946b..2f211978d 100644
--- a/include/types/sample.h
+++ b/include/types/sample.h
@@ -243,6 +243,7 @@ struct sample_conv {
 		       struct sample *smp);       /* process function */
 	unsigned int arg_mask;                    /* arguments (ARG*()) */
 	int (*val_args)(struct arg *arg_p,
+	                struct sample_conv *smp_conv,
 			char **err_msg);          /* argument validation function */
 	unsigned int in_type;                     /* expected input sample type */
 	unsigned int out_type;                    /* output sample type */
diff --git a/src/acl.c b/src/acl.c
index 9f487a309..9ea082a30 100644
--- a/src/acl.c
+++ b/src/acl.c
@@ -1277,7 +1277,7 @@ struct acl_expr *parse_acl_expr(const char **args, char **err, struct arg_list *
 					if (!conv_expr->arg_p)
 						conv_expr->arg_p = empty_arg_list;
 
-					if (conv->val_args && !conv->val_args(conv_expr->arg_p, &err_msg)) {
+					if (conv->val_args && !conv->val_args(conv_expr->arg_p, conv, &err_msg)) {
 						memprintf(err, "ACL keyword '%s' : invalid args in conv method '%s' : %s.",
 						          expr->kw, ckw, err_msg);
 						free(err_msg);
diff --git a/src/sample.c b/src/sample.c
index ac0e52a80..162c94953 100644
--- a/src/sample.c
+++ b/src/sample.c
@@ -745,7 +745,7 @@ struct sample_expr *sample_parse_expr(char **str, int *idx, char *err, int err_s
 			if (!conv_expr->arg_p)
 				conv_expr->arg_p = empty_arg_list;
 
-			if (conv->val_args && !conv->val_args(conv_expr->arg_p, &err_msg)) {
+			if (conv->val_args && !conv->val_args(conv_expr->arg_p, conv, &err_msg)) {
 				snprintf(err, err_size, "invalid args in conv method '%s' : %s.", ckw, err_msg);
 				free(err_msg);
 				goto out_error;