diff --git a/tools/testing/selftests/net/lib.sh b/tools/testing/selftests/net/lib.sh
index 114b927fee256..915f319bcc8bf 100644
--- a/tools/testing/selftests/net/lib.sh
+++ b/tools/testing/selftests/net/lib.sh
@@ -167,26 +167,30 @@ cleanup_all_ns()
 # setup_ns local remote
 setup_ns()
 {
-	local ns=""
 	local ns_name=""
 	local ns_list=()
 	for ns_name in "$@"; do
+		# avoid conflicts with local var: internal error
+		if [ "${ns_name}" = "ns_name" ]; then
+			echo "Failed to setup namespace '${ns_name}': invalid name"
+			cleanup_ns "${ns_list[@]}"
+			exit $ksft_fail
+		fi
+
 		# Some test may setup/remove same netns multi times
 		if [ -z "${!ns_name}" ]; then
-			ns="${ns_name,,}-$(mktemp -u XXXXXX)"
-			eval "${ns_name}=${ns}"
+			eval "${ns_name}=${ns_name,,}-$(mktemp -u XXXXXX)"
 		else
-			ns="${!ns_name}"
-			cleanup_ns "$ns"
+			cleanup_ns "${!ns_name}"
 		fi
 
-		if ! ip netns add "$ns"; then
+		if ! ip netns add "${!ns_name}"; then
 			echo "Failed to create namespace $ns_name"
 			cleanup_ns "${ns_list[@]}"
 			return $ksft_skip
 		fi
-		ip -n "$ns" link set lo up
-		ns_list+=("$ns")
+		ip -n "${!ns_name}" link set lo up
+		ns_list+=("${!ns_name}")
 	done
 	NS_LIST+=("${ns_list[@]}")
 }