diff --git a/bsc-nat/BSC_MS_Simulation.ttcn b/bsc-nat/BSC_MS_Simulation.ttcn
index 453f30404..058257672 100644
--- a/bsc-nat/BSC_MS_Simulation.ttcn
+++ b/bsc-nat/BSC_MS_Simulation.ttcn
@@ -10,6 +10,7 @@ module BSC_MS_Simulation {
  * SPDX-License-Identifier: GPL-2.0-or-later
  */
 
+import from Osmocom_Types all;
 import from IPL4asp_Types all;
 
 import from IPA_Emulation all;
@@ -83,6 +84,10 @@ runs on BSC_CT {
 	f_ctrl_trap(SCCPLITE_IPA_CTRL, "bts.0.location-state",
 		    "1234567,fix3d,0.340000,0.560000,0.780000,operational,unlocked,on,001,01");
 	f_ctrl_exp_set(SCCPLITE_IPA_CTRL, "rf_locked", "1", "1");
+	/* Leave some time for SET_REPLY to reach the other side before closing
+	   conn towards BSC-NAT, otherwise TCP FIN is sent before SET_REPLY and
+	   bsc-nat sends a CTRL ERR to whoever sent the SET cmd. */
+	f_sleep(1.0);
 }
 
 function main(charstring remote_ip, PortNumber remote_port,