diff --git a/include/proto/arg.h b/include/proto/arg.h
index e051de5..91c1acd 100644
--- a/include/proto/arg.h
+++ b/include/proto/arg.h
@@ -48,6 +48,9 @@
 #define ARG5(m, t1, t2, t3, t4, t5) \
 	(ARG4(m, t1, t2, t3, t4) + (ARGT_##t5 << (ARGM_BITS + ARGT_BITS * 4)))
 
+/* Mapping between argument number and literal description. */
+extern const char *arg_type_names[];
+
 /* This dummy arg list may be used by default when no arg is found, it helps
  * parsers by removing pointer checks.
  */
diff --git a/include/proto/payload.h b/include/proto/payload.h
index 4b658d4..fd89c88 100644
--- a/include/proto/payload.h
+++ b/include/proto/payload.h
@@ -27,6 +27,7 @@
 #include <types/session.h>
 
 int fetch_rdp_cookie_name(struct session *s, struct sample *smp, const char *cname, int clen);
+int val_payload_lv(struct arg *arg, char **err_msg);
 
 #endif /* _PROTO_PROTO_PAYLOAD_H */
 
diff --git a/include/proto/proto_http.h b/include/proto/proto_http.h
index 579a6cb..9e99ba1 100644
--- a/include/proto/proto_http.h
+++ b/include/proto/proto_http.h
@@ -131,6 +131,7 @@
 
 struct http_req_action_kw *action_http_req_custom(const char *kw);
 struct http_res_action_kw *action_http_res_custom(const char *kw);
+int val_hdr(struct arg *arg, char **err_msg);
 
 static inline void http_req_keywords_register(struct http_req_action_kw_list *kw_list)
 {
diff --git a/src/arg.c b/src/arg.c
index e609ac5..e212f6b 100644
--- a/src/arg.c
+++ b/src/arg.c
@@ -17,7 +17,7 @@
 #include <common/standard.h>
 #include <proto/arg.h>
 
-static const char *arg_type_names[ARGT_NBTYPES] = {
+const char *arg_type_names[ARGT_NBTYPES] = {
 	[ARGT_STOP] = "end of arguments",
 	[ARGT_UINT] = "unsigned integer",
 	[ARGT_SINT] = "signed integer",
diff --git a/src/payload.c b/src/payload.c
index 2654170..53c9972 100644
--- a/src/payload.c
+++ b/src/payload.c
@@ -631,7 +631,7 @@
  * error, that the caller is responsible for freeing. The initial location must
  * either be freeable or NULL.
  */
-static int val_payload_lv(struct arg *arg, char **err_msg)
+int val_payload_lv(struct arg *arg, char **err_msg)
 {
 	if (!arg[1].data.uint) {
 		memprintf(err_msg, "payload length must be > 0");
diff --git a/src/proto_http.c b/src/proto_http.c
index f87583f..de219e3 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -11364,7 +11364,7 @@
  * error message in case of error, that the caller is responsible for freeing.
  * The initial location must either be freeable or NULL.
  */
-static int val_hdr(struct arg *arg, char **err_msg)
+int val_hdr(struct arg *arg, char **err_msg)
 {
 	if (arg && arg[1].type == ARGT_SINT && arg[1].data.sint < -MAX_HDR_HISTORY) {
 		memprintf(err_msg, "header occurrence must be >= %d", -MAX_HDR_HISTORY);