diff --git a/targets/SIMU/USER/Makefile b/targets/SIMU/USER/Makefile
index 8cdbcf6bfa..75a3e3710c 100644
--- a/targets/SIMU/USER/Makefile
+++ b/targets/SIMU/USER/Makefile
@@ -24,6 +24,7 @@ CFLAGS += -g -ggdb -DDEBUG_PHY -DDEBUG_MEAS
 CFLAGS += -DRRC_MSG_PRINT
 CFLAGS += -DPDCP_MSG_PRINT
 #CFLAGS += -DTRACE_RLC_UM_PDU
+#CFLAGS += -DTRACE_RLC_AM_PDU
 endif 
 
 ifeq ($(MSG_PRINT),1)