diff --git a/include/osmocom/gsm/protocol/gsm_29_118.h b/include/osmocom/gsm/protocol/gsm_29_118.h
index 9adb90f..1583588 100644
--- a/include/osmocom/gsm/protocol/gsm_29_118.h
+++ b/include/osmocom/gsm/protocol/gsm_29_118.h
@@ -181,4 +181,4 @@
  * See also: RFC1123 Section 2.1 Host Names and Numbers */
 #define SGS_VLR_NAME_MAXLEN 255
 
-const struct tlv_definition sgsap_ie_tlvdef;
+extern const struct tlv_definition sgsap_ie_tlvdef;