diff --git a/include/osmocore/msgb.h b/include/osmocore/msgb.h
index 754918e..31db719 100644
--- a/include/osmocore/msgb.h
+++ b/include/osmocore/msgb.h
@@ -46,6 +46,7 @@
 	union {
 		unsigned char *smsh;
 		unsigned char *llch;
+		unsigned char *l4h;
 	};
 
 	/* the layer 5 header, GPRS: GMM header */