abis_nm.h: Add include to gsm_utils.h
diff --git a/include/osmocom/gsm/abis_nm.h b/include/osmocom/gsm/abis_nm.h
index 8534557..3f5335e 100644
--- a/include/osmocom/gsm/abis_nm.h
+++ b/include/osmocom/gsm/abis_nm.h
@@ -2,6 +2,7 @@
 #define _OSMO_GSM_ABIS_NM_H
 
 #include <osmocom/gsm/tlv.h>
+#include <osmocom/gsm/gsm_utils.h>
 #include <osmocom/gsm/protocol/gsm_12_21.h>
 
 enum abis_nm_msgtype;