diff --git a/scripts/start_qemu_vm.sh b/scripts/start_qemu_vm.sh
index e0694b1..ecbddb8 100755
--- a/scripts/start_qemu_vm.sh
+++ b/scripts/start_qemu_vm.sh
@@ -30,8 +30,8 @@ add_nft_rules() {
 
   # TODO: This will handle only one IP per VM. If you add multiple IPs, fix this.
   # Also, we wish you good luck. We know this code is complicated. We tried, ok?
-  ipv4_addr=$(echo $PARAMS | grep -m 1 -oE "detee_net_eth${nic_index}=[0-9]{1,3}\.[0-9a-f\.]+" | cut -d "=" -f2 )
-  ipv6_addr=$(echo $PARAMS | grep -m 1 -oE "detee_net_eth${nic_index}=[0-9a-f]{1,4}\:[0-9a-f\:]+" | cut -d "=" -f2 )
+  ipv4_addr=$(echo $PARAMS | grep -m 1 -oP "detee_net_eth${nic_index}=[0-9]{1,3}\.[0-9a-f\.]+" | cut -d "=" -f2 )
+  ipv6_addr=$(echo $PARAMS | grep -m 1 -oP "detee_net_eth${nic_index}=[0-9a-f]{1,4}\:[0-9a-f\:]+" | cut -d "=" -f2 )
 
   [[ -n "$ipv4_addr" ]] && {
     nft add rule netdev deteemacvtap ${ifname}_in ip daddr != $ipv4_addr drop