diff --git a/easyrsa3/easyrsa b/easyrsa3/easyrsa
index 4db2bb7..304e54e 100755
--- a/easyrsa3/easyrsa
+++ b/easyrsa3/easyrsa
@@ -2343,7 +2343,7 @@ default_server_san() {
 		awk -F'=' '/^  *CN=/{print $2}'
 		)"
 
-	if echo "$cn" | grep -E -q '^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$'; then
+	if echo "$cn" | grep -E -q '^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$'; then
 		print "subjectAltName = IP:$cn"
 	else
 		print "subjectAltName = DNS:$cn"