diff --git a/include/osmocom/msc/transaction.h b/include/osmocom/msc/transaction.h
index c63ef5b..9278b64 100644
--- a/include/osmocom/msc/transaction.h
+++ b/include/osmocom/msc/transaction.h
@@ -27,7 +27,7 @@
 	     ##args)
 
 #define LOG_TRANS(trans, level, fmt, args...) \
-	     LOG_TRANS_CAT(trans, (trans)->log_subsys, level, fmt, ##args)
+	     LOG_TRANS_CAT(trans, (trans) ? (trans)->log_subsys : DMSC, level, fmt, ##args)
 
 enum bridge_state {
 	BRIDGE_STATE_NONE,