diff --git a/lib/gtp/asn_msg.h b/lib/core/include/core_tlv_msg.h
similarity index 95%
rename from lib/gtp/asn_msg.h
rename to lib/core/include/core_tlv_msg.h
index aacc1a4d52..d3d7f1efe3 100644
--- a/lib/gtp/asn_msg.h
+++ b/lib/core/include/core_tlv_msg.h
@@ -1,18 +1,19 @@
 #ifndef __TLV_MSG_H__
 #define __TLV_MSG_H__
 
+#include "core_tlv.h"
 #include "core_pkbuf.h"
 
-#define TLV_HEADER_LEN 12
-#define TLV_VARIABLE 0
-
 #ifdef __cplusplus
 extern "C" {
 #endif /* __cplusplus */
 
-typedef struct _tlv_header_t {
-    c_uint64_t set_ind;
-} tlv_header_t;
+#define TLV_MAX_HEADROOM 16
+
+#define TLV_VARIABLE_LEN 0
+
+#define TLV_MAX_MORE 8
+#define TLV_1_OR_MORE(__v) __v[TLV_MAX_MORE]
 
 #define VALUE_SET(__m, __value) \
     __m.v = __value; __m.h.set_ind = 1
@@ -69,6 +70,12 @@ typedef struct _tlv_desc_t {
     void *child_descs[];
 } tlv_desc_t;
 
+extern tlv_desc_t tlv_desc_more;
+
+typedef struct _tlv_header_t {
+    c_uint64_t set_ind;
+} tlv_header_t;
+
 /* 8-bit Unsigned integer */
 typedef struct _tlv_uint8_t {
     tlv_header_t h;
@@ -129,11 +136,6 @@ typedef struct _tlv_null {
     tlv_header_t h;
 } tlv_null_t;
 
-#define TLV_MORE 8
-#define TLV_1_OR_MORE(__v) __v[TLV_MORE]
-
-extern tlv_desc_t tlv_desc_more;
-
 CORE_DECLARE(status_t) tlv_build_msg(
         pkbuf_t **msg, tlv_desc_t *msg_desc, void *asn);
 
diff --git a/lib/core/src/Makefile.am b/lib/core/src/Makefile.am
index 8f136e46be..f0f66a9c7a 100644
--- a/lib/core/src/Makefile.am
+++ b/lib/core/src/Makefile.am
@@ -16,10 +16,11 @@ libcore_la_SOURCES = \
 	../include/core_rwlock.h ../include/core_semaphore.h ../include/core_sha1.h \
 	../include/core_sha1_hmac.h ../include/core_sha2.h ../include/core_sha2_hmac.h \
 	../include/core_signal.h ../include/core_thread.h ../include/core_time.h \
-	../include/core_timer.h ../include/core_tlv.h ../include/core_version.h
+	../include/core_timer.h ../include/core_tlv.h ../include/core_tlv_msg.h \
+	../include/core_version.h
 
 nodist_libcore_la_SOURCES = \
-    debug.c fsm.c msgq.c ringbuf.c timer.c tlv.c \
+    debug.c fsm.c msgq.c ringbuf.c timer.c tlv.c tlv_msg.c \
 	aes.c aes_cmac.c sha1.c sha1_hmac.c sha2.c sha2_hmac.c misc.c
 
 libcore_la_DEPENDENCIES = \
diff --git a/lib/gtp/asn_msg.c b/lib/core/src/tlv_msg.c
similarity index 99%
rename from lib/gtp/asn_msg.c
rename to lib/core/src/tlv_msg.c
index 5582e1da94..64b228ad4f 100644
--- a/lib/gtp/asn_msg.c
+++ b/lib/core/src/tlv_msg.c
@@ -1,8 +1,7 @@
 #define TRACE_MODULE _tlv_msg
-#include "core_debug.h"
-#include "core_tlv.h"
 
-#include "asn_msg.h"
+#include "core_debug.h"
+#include "core_tlv_msg.h"
 
 tlv_desc_t tlv_desc_more = 
 {
@@ -258,7 +257,7 @@ status_t tlv_build_msg(pkbuf_t **msg, tlv_desc_t *msg_desc, void *asn)
             "Can't build TLV message");
 
     length = tlv_calc_length(root, TLV_MODE_T1_L2_I1);
-    *msg = pkbuf_alloc(TLV_HEADER_LEN, length);
+    *msg = pkbuf_alloc(TLV_MAX_HEADROOM, length);
     d_assert(*msg, tlv_free_all(root); return CORE_ENOMEM,
             "pkbuf_alloc() failed");
     (*msg)->len = length;
diff --git a/lib/gtp/Makefile.am b/lib/gtp/Makefile.am
index 75ca8f4b1e..3515e171ac 100644
--- a/lib/gtp/Makefile.am
+++ b/lib/gtp/Makefile.am
@@ -3,10 +3,10 @@
 noinst_LTLIBRARIES = libgtp.la
 
 libgtp_la_SOURCES = \
-	asn_msg.h asn_tlv_desc.h
+	gtpv2c_tlv.h
 
 nodist_libgtp_la_SOURCES = \
-	asn_msg.c asn_tlv_desc.c
+	gtpv2c_tlv.c
 
 AM_CPPFLAGS = \
     -I$(top_srcdir)/lib/core/include \
diff --git a/lib/gtp/asn_tlv_desc.c b/lib/gtp/gtpv2c_tlv.c
similarity index 97%
rename from lib/gtp/asn_tlv_desc.c
rename to lib/gtp/gtpv2c_tlv.c
index 6ec70d5152..73b8e4bdb3 100644
--- a/lib/gtp/asn_tlv_desc.c
+++ b/lib/gtp/gtpv2c_tlv.c
@@ -1,4 +1,4 @@
-#include "asn_tlv_desc.h"
+#include "gtpv2c_tlv.h"
 
 tlv_desc_t tlv_desc_authorization_policy_support = 
 {
diff --git a/lib/gtp/asn_tlv_desc.h b/lib/gtp/gtpv2c_tlv.h
similarity index 81%
rename from lib/gtp/asn_tlv_desc.h
rename to lib/gtp/gtpv2c_tlv.h
index 899392e064..9d299e1fcb 100644
--- a/lib/gtp/asn_tlv_desc.h
+++ b/lib/gtp/gtpv2c_tlv.h
@@ -1,7 +1,7 @@
-#ifndef __TLV_TLV_DESC_H__
-#define __TLV_TLV_DESC_H__
+#ifndef __GTPV2C_TLV_H__
+#define __GTPV2C_TLV_H__
 
-#include "asn_msg.h"
+#include "core_tlv_msg.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -13,7 +13,7 @@ typedef tlv_uint8_t tlv_authorization_policy_support_t;
 extern tlv_desc_t tlv_desc_authorization_policy_support;
 
 #define TLV_MS_SECURITY_HISTORY_TYPE 108
-#define TLV_MS_SECURITY_HISTORY_LEN TLV_VARIABLE
+#define TLV_MS_SECURITY_HISTORY_LEN TLV_VARIABLE_LEN
 typedef struct _tlv_ms_security_history_t {
     tlv_header_t h;
     tlv_authorization_policy_support_t authorization_policy_support;
@@ -21,7 +21,7 @@ typedef struct _tlv_ms_security_history_t {
 extern tlv_desc_t tlv_desc_ms_security_history;
 
 #define TLV_MS_INFO_TYPE 103
-#define TLV_MS_INFO_LEN TLV_VARIABLE
+#define TLV_MS_INFO_LEN TLV_VARIABLE_LEN
 typedef struct _tlv_ms_info_t {
     tlv_header_t h;
     tlv_ms_security_history_t ms_security_history;
@@ -29,12 +29,12 @@ typedef struct _tlv_ms_info_t {
 extern tlv_desc_t tlv_desc_ms_info;
 
 #define TLV_BS_ID_TYPE 25
-#define TLV_BS_ID_LEN TLV_VARIABLE
+#define TLV_BS_ID_LEN TLV_VARIABLE_LEN
 typedef tlv_octets_t tlv_bs_id_t;
 extern tlv_desc_t tlv_desc_bs_id;
 
 #define TLV_BS_INFO_TYPE 26
-#define TLV_BS_INFO_LEN TLV_VARIABLE
+#define TLV_BS_INFO_LEN TLV_VARIABLE_LEN
 typedef struct _tlv_bs_info_t {
     tlv_header_t h;
     tlv_bs_id_t bs_id;
@@ -52,4 +52,4 @@ extern tlv_desc_t tlv_desc_msg_ms_preattachment_req;
 }
 #endif /* __cplusplus */
 
-#endif /* __TLV_TLV_DESC_H__ */
+#endif /* __GTPV2C_TLV_H__ */
diff --git a/test/gtp_message_test.c b/test/gtp_message_test.c
index 10bc2fa89f..ae6a71022e 100644
--- a/test/gtp_message_test.c
+++ b/test/gtp_message_test.c
@@ -3,8 +3,7 @@
 #include "core_debug.h"
 
 #include "testutil.h"
-#include "asn_msg.h"
-#include "asn_tlv_desc.h"
+#include "gtpv2c_tlv.h"
 
 static void gtp_message_test1(abts_case *tc, void *data)
 {