diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index beec41f6662a..28da9df797ae 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -63,6 +63,7 @@ unset fastclose
 unset fullmesh
 unset speed
 unset bind_addr
+unset ifaces_nr
 unset join_syn_rej
 unset join_csum_ns1
 unset join_csum_ns2
@@ -146,7 +147,7 @@ init_partial()
 	# ns1eth4    ns2eth4
 
 	local i
-	for i in $(seq 1 4); do
+	for i in $(seq 1 "${ifaces_nr:-4}"); do
 		ip link add ns1eth$i netns "$ns1" type veth peer name ns2eth$i netns "$ns2"
 		ip -net "$ns1" addr add 10.0.$i.1/24 dev ns1eth$i
 		ip -net "$ns1" addr add dead:beef:$i::1/64 dev ns1eth$i nodad
@@ -165,7 +166,7 @@ init_partial()
 init_shapers()
 {
 	local i
-	for i in $(seq 1 4); do
+	for i in $(seq 1 "${ifaces_nr:-4}"); do
 		tc -n $ns1 qdisc add dev ns1eth$i root netem rate 20mbit delay 1ms
 		tc -n $ns2 qdisc add dev ns2eth$i root netem rate 20mbit delay 1ms
 	done