diff --git a/src/wg-quick/linux.bash b/src/wg-quick/linux.bash
index 34fa5f9d..300e6664 100755
--- a/src/wg-quick/linux.bash
+++ b/src/wg-quick/linux.bash
@@ -238,7 +238,7 @@ add_default() {
 	printf -v restore '%sCOMMIT\n*mangle\n-I POSTROUTING -m mark --mark %d -p udp -j CONNMARK --save-mark %s\n-I PREROUTING -p udp -j CONNMARK --restore-mark %s\nCOMMIT\n' "$restore" $table "$marker" "$marker"
 	printf -v nftcmd '%sadd rule %s %s postmangle meta l4proto udp mark %d ct mark set mark \n' "$nftcmd" "$pf" "$nftable" $table
 	printf -v nftcmd '%sadd rule %s %s premangle meta l4proto udp meta mark set ct mark \n' "$nftcmd" "$pf" "$nftable"
-	[[ $proto == -4 ]] && cmd sysctl -q net.ipv4.conf.all.src_valid_mark=1
+	[[ $proto == -4 ]] && [[ $(sysctl -n net.ipv4.conf.all.src_valid_mark) != 1 ]] && cmd sysctl -q net.ipv4.conf.all.src_valid_mark=1
 	if type -p nft >/dev/null; then
 		cmd nft -f <(echo -n "$nftcmd")
 	else