diff --git a/tools/testing/selftests/net/mptcp/diag.sh b/tools/testing/selftests/net/mptcp/diag.sh
index c3b69b64042c..afe862895946 100755
--- a/tools/testing/selftests/net/mptcp/diag.sh
+++ b/tools/testing/selftests/net/mptcp/diag.sh
@@ -1,10 +1,14 @@
 #!/bin/bash
 # SPDX-License-Identifier: GPL-2.0
 
+# Double quotes to prevent globbing and word splitting is recommended in new
+# code but we accept it, especially because there were too many before having
+# address all other issues detected by shellcheck.
+#shellcheck disable=SC2086
+
 . "$(dirname "${0}")/mptcp_lib.sh"
 
 ns=""
-ksft_skip=4
 test_cnt=1
 timeout_poll=30
 timeout_test=$((timeout_poll * 2 + 1))
@@ -24,6 +28,8 @@ flush_pids()
 	done
 }
 
+# This function is used in the cleanup trap
+#shellcheck disable=SC2317
 cleanup()
 {
 	ip netns pids "${ns}" | xargs --no-run-if-empty kill -SIGKILL &>/dev/null
@@ -174,7 +180,7 @@ chk_msk_inuse()
 	expected=$((expected + listen_nr))
 
 	for _ in $(seq 10); do
-		if [ $(get_msk_inuse) -eq $expected ];then
+		if [ "$(get_msk_inuse)" -eq $expected ]; then
 			break
 		fi
 		sleep 0.1
@@ -260,7 +266,7 @@ chk_msk_inuse 0 "1->0"
 chk_msk_cestab 0 "1->0"
 
 NR_CLIENTS=100
-for I in `seq 1 $NR_CLIENTS`; do
+for I in $(seq 1 $NR_CLIENTS); do
 	echo "a" | \
 		timeout ${timeout_test} \
 			ip netns exec $ns \
@@ -269,7 +275,7 @@ for I in `seq 1 $NR_CLIENTS`; do
 done
 mptcp_lib_wait_local_port_listen $ns $((NR_CLIENTS + 10001))
 
-for I in `seq 1 $NR_CLIENTS`; do
+for I in $(seq 1 $NR_CLIENTS); do
 	echo "b" | \
 		timeout ${timeout_test} \
 			ip netns exec $ns \