diff --git a/include/osmocom/msc/gsm_data.h b/include/osmocom/msc/gsm_data.h
index 16e83f3..2cddd25 100644
--- a/include/osmocom/msc/gsm_data.h
+++ b/include/osmocom/msc/gsm_data.h
@@ -212,7 +212,7 @@
 		/* The connection identifier that is used
 		 * to reference the SCCP connection that is
 		 * associated with this subscriber connection */
-		int conn_id;
+		uint32_t conn_id;
 	} a;
 };