diff --git a/acme/dns_challenge.go b/acme/dns_challenge.go
index 7c4cb80d..13373974 100644
--- a/acme/dns_challenge.go
+++ b/acme/dns_challenge.go
@@ -11,7 +11,6 @@ import (
 	"time"
 
 	"github.com/miekg/dns"
-	"golang.org/x/net/publicsuffix"
 )
 
 type preCheckDNSFunc func(fqdn, value string) (bool, error)
@@ -242,10 +241,6 @@ func FindZoneByFqdn(fqdn string, nameservers []string) (string, error) {
 	labelIndexes := dns.Split(fqdn)
 	for _, index := range labelIndexes {
 		domain := fqdn[index:]
-		// Give up if we have reached the TLD
-		if isTLD(domain) {
-			break
-		}
 
 		in, err := dnsQuery(domain, dns.TypeSOA, nameservers, true)
 		if err != nil {
@@ -273,14 +268,6 @@ func FindZoneByFqdn(fqdn string, nameservers []string) (string, error) {
 	return "", fmt.Errorf("Could not find the start of authority")
 }
 
-func isTLD(domain string) bool {
-	publicsuffix, _ := publicsuffix.PublicSuffix(UnFqdn(domain))
-	if publicsuffix == UnFqdn(domain) {
-		return true
-	}
-	return false
-}
-
 // ClearFqdnCache clears the cache of fqdn to zone mappings. Primarily used in testing.
 func ClearFqdnCache() {
 	fqdnToZone = map[string]string{}
diff --git a/acme/dns_challenge_test.go b/acme/dns_challenge_test.go
index 597aaac1..4a2a7fea 100644
--- a/acme/dns_challenge_test.go
+++ b/acme/dns_challenge_test.go
@@ -37,14 +37,6 @@ var lookupNameserversTestsErr = []struct {
 	{"_null.n0n0.",
 		"Could not determine the zone",
 	},
-	// invalid domain
-	{"_null.com.",
-		"Could not determine the zone",
-	},
-	// invalid domain
-	{"in-valid.co.uk.",
-		"Could not determine the zone",
-	},
 }
 
 var findZoneByFqdnTests = []struct {
@@ -53,6 +45,7 @@ var findZoneByFqdnTests = []struct {
 }{
 	{"mail.google.com.", "google.com."}, // domain is a CNAME
 	{"foo.google.com.", "google.com."},  // domain is a non-existent subdomain
+	{"example.com.ac.", "ac."},          // domain is a eTLD
 }
 
 var checkAuthoritativeNssTests = []struct {