diff --git a/files/usr/bin/blue-merle b/files/usr/bin/blue-merle
index 72b45de..2563180 100644
--- a/files/usr/bin/blue-merle
+++ b/files/usr/bin/blue-merle
@@ -44,6 +44,14 @@ while [[ "$answer" -eq 1 ]]; do
 	fi
 done
 
+## We have just disabled the modem so it should not log on to any network.
+## We set a random IMEI now only to have it overwritten very soon after
+## the SIM card has been replaced. We intend to prevent an accidential
+## leak of the new SIM's IMSI with the old IMEI just in case the modem
+## accidentally tried to log in to the network.
+python3 /lib/blue-merle/imei_generate.py -r
+
+
 echo -n "Please now replace the SIM card and press any key to continue. "
 read answer
 
diff --git a/files/usr/bin/blue-merle-switch-stage1 b/files/usr/bin/blue-merle-switch-stage1
index 7d1e7c9..901fca1 100644
--- a/files/usr/bin/blue-merle-switch-stage1
+++ b/files/usr/bin/blue-merle-switch-stage1
@@ -61,6 +61,12 @@ while [[ "$answer" -eq 1 ]]; do
 	fi
 done
 
+## We generate a random IMEI to prevent a leak of the
+## new SIM's IMSI under the old IMEI in case the modem
+## still talks to the network
+python3 /lib/blue-merle/imei_generate.py -r
+
+
 mcu_send_message "Replace the SIM card. Then pull the switch."
 
 echo done > /tmp/blue-merle-stage1