diff --git a/dns/iputil.go b/dns/iputil.go
index 7967b44a..3c34cf16 100644
--- a/dns/iputil.go
+++ b/dns/iputil.go
@@ -37,8 +37,8 @@ func ResolveIPv4(host string) (net.IP, error) {
 	}
 
 	for _, ip := range ipAddrs {
-		if len(ip) == net.IPv4len {
-			return ip, nil
+		if ip4 := ip.To4(); ip4 != nil {
+			return ip4, nil
 		}
 	}
 
@@ -71,7 +71,7 @@ func ResolveIPv6(host string) (net.IP, error) {
 	}
 
 	for _, ip := range ipAddrs {
-		if len(ip) == net.IPv6len {
+		if ip.To4() == nil {
 			return ip, nil
 		}
 	}
diff --git a/dns/resolver.go b/dns/resolver.go
index 0ba23420..2276f789 100644
--- a/dns/resolver.go
+++ b/dns/resolver.go
@@ -222,9 +222,10 @@ func (r *Resolver) fallbackExchange(m *D.Msg) (msg *D.Msg, err error) {
 func (r *Resolver) resolveIP(host string, dnsType uint16) (ip net.IP, err error) {
 	ip = net.ParseIP(host)
 	if ip != nil {
-		if dnsType == D.TypeAAAA && len(ip) == net.IPv6len {
+		isIPv4 := ip.To4() != nil
+		if dnsType == D.TypeAAAA && !isIPv4 {
 			return ip, nil
-		} else if dnsType == D.TypeA && len(ip) == net.IPv4len {
+		} else if dnsType == D.TypeA && isIPv4 {
 			return ip, nil
 		}
 	}