diff --git a/tools/testing/selftests/net/mptcp/diag.sh b/tools/testing/selftests/net/mptcp/diag.sh
index 95b498efacd1f2..649017addb3e2a 100755
--- a/tools/testing/selftests/net/mptcp/diag.sh
+++ b/tools/testing/selftests/net/mptcp/diag.sh
@@ -182,6 +182,16 @@ chk_msk_inuse()
 	__chk_nr get_msk_inuse $expected "$msg" 0
 }
 
+# $1: ns, $2: cestab nr
+chk_msk_cestab()
+{
+	local ns=$1
+	local cestab=$2
+
+	__chk_nr "mptcp_lib_get_counter ${ns} MPTcpExtMPCurrEstab" \
+		 "${cestab}" "....chk ${cestab} cestab" ""
+}
+
 wait_connected()
 {
 	local listener_ns="${1}"
@@ -219,9 +229,11 @@ chk_msk_nr 2 "after MPC handshake "
 chk_msk_remote_key_nr 2 "....chk remote_key"
 chk_msk_fallback_nr 0 "....chk no fallback"
 chk_msk_inuse 2 "....chk 2 msk in use"
+chk_msk_cestab $ns 2
 flush_pids
 
 chk_msk_inuse 0 "....chk 0 msk in use after flush"
+chk_msk_cestab $ns 0
 
 echo "a" | \
 	timeout ${timeout_test} \
@@ -237,9 +249,11 @@ echo "b" | \
 wait_connected $ns 10001
 chk_msk_fallback_nr 1 "check fallback"
 chk_msk_inuse 1 "....chk 1 msk in use"
+chk_msk_cestab $ns 1
 flush_pids
 
 chk_msk_inuse 0 "....chk 0 msk in use after flush"
+chk_msk_cestab $ns 0
 
 NR_CLIENTS=100
 for I in `seq 1 $NR_CLIENTS`; do
@@ -261,9 +275,11 @@ done
 
 wait_msk_nr $((NR_CLIENTS*2)) "many msk socket present"
 chk_msk_inuse $((NR_CLIENTS*2)) "....chk many msk in use"
+chk_msk_cestab $ns $((NR_CLIENTS*2))
 flush_pids
 
 chk_msk_inuse 0 "....chk 0 msk in use after flush"
+chk_msk_cestab $ns 0
 
 mptcp_lib_result_print_all_tap
 exit $ret