diff --git a/library/RSL_Emulation.ttcn b/library/RSL_Emulation.ttcn
index 969dbce..31647df 100644
--- a/library/RSL_Emulation.ttcn
+++ b/library/RSL_Emulation.ttcn
@@ -612,6 +612,8 @@
 				log("Storing an RSL message in the waiting queue");
 				WaitingQueue := WaitingQueue & { rx_rsl };
 			} else {
+				log("Error: RSL for unknown Dchan (streamId ", rx_rsl.streamId, ", chan_nr ",
+					   rx_rsl.rsl.ies[0].body.chan_nr, "): ", rx_rsl);
 				setverdict(fail, "RSL for unknown Dchan");
 				mtc.stop;
 			}