diff --git a/mxresolv/mxresolv.go b/mxresolv/mxresolv.go
index 2b9aaa5..da9b3f0 100644
--- a/mxresolv/mxresolv.go
+++ b/mxresolv/mxresolv.go
@@ -45,7 +45,7 @@ func init() {
 // does not have explicit MX records, and its A record is returned instead.
 //
 // It uses an LRU cache with a timeout to reduce the number of network requests.
-func Lookup(ctx context.Context, domain string) ([]string, bool, error) {
+func Lookup(ctx context.Context, domain string) (mxHosts []string, implicit bool, err error) {
 	mxRecords, implicit, err := LookupWithPref(ctx, domain)
 	if err != nil {
 		return nil, false, err
@@ -63,7 +63,7 @@ func Lookup(ctx context.Context, domain string) ([]string, bool, error) {
 // explicit MX records, and its A record is used instead.
 //
 // It uses an LRU cache with a timeout to reduce the number of network requests.
-func LookupWithPref(ctx context.Context, domainName string) ([]*net.MX, bool, error) {
+func LookupWithPref(ctx context.Context, domainName string) (mxRecords []*net.MX, implicit bool, err error) {
 	if cachedVal, ok := lookupResultCache.Get(domainName); ok {
 		cachedLookupResult := cachedVal.(lookupResult)
 		return cachedLookupResult.mxRecords, cachedLookupResult.implicit, cachedLookupResult.err
@@ -73,14 +73,14 @@ func LookupWithPref(ctx context.Context, domainName string) ([]*net.MX, bool, er
 	if err != nil {
 		return nil, false, errors.Wrap(err, "invalid domain name")
 	}
-	mxRecords, err := lookupMX(Resolver, ctx, asciiDomainName)
+	mxRecords, err = lookupMX(Resolver, ctx, asciiDomainName)
 	if err != nil {
 		var netDNSError *net.DNSError
 		if errors.As(err, &netDNSError) && netDNSError.IsNotFound {
 			if _, err := Resolver.LookupIPAddr(ctx, asciiDomainName); err != nil {
 				return cacheAndReturn(domainName, nil, false, errors.WithStack(err))
 			}
-			return cacheAndReturn(domainName, []*net.MX{{asciiDomainName, 1}}, true, nil)
+			return cacheAndReturn(domainName, []*net.MX{{Host: asciiDomainName, Pref: 1}}, true, nil)
 		}
 		if mxRecords == nil {
 			return cacheAndReturn(domainName, nil, false, errors.WithStack(err))
diff --git a/mxresolv/mxresolv_test.go b/mxresolv/mxresolv_test.go
index cc3c080..68a4c95 100644
--- a/mxresolv/mxresolv_test.go
+++ b/mxresolv/mxresolv_test.go
@@ -121,49 +121,49 @@ func TestLookupWithPref(t *testing.T) {
 		desc:         "MX record preference is respected",
 		inDomainName: "test-mx.definbox.com",
 		outMXHosts: []*net.MX{
-			{"mxa.definbox.com", 1}, {"mxe.definbox.com", 1}, {"mxi.definbox.com", 1},
-			{"mxc.definbox.com", 2},
-			{"mxb.definbox.com", 3}, {"mxd.definbox.com", 3}, {"mxf.definbox.com", 3}, {"mxg.definbox.com", 3}, {"mxh.definbox.com", 3},
+			{Host: "mxa.definbox.com", Pref: 1}, {Host: "mxe.definbox.com", Pref: 1}, {Host: "mxi.definbox.com", Pref: 1},
+			{Host: "mxc.definbox.com", Pref: 2},
+			{Host: "mxb.definbox.com", Pref: 3}, {Host: "mxd.definbox.com", Pref: 3}, {Host: "mxf.definbox.com", Pref: 3}, {Host: "mxg.definbox.com", Pref: 3}, {Host: "mxh.definbox.com", Pref: 3},
 		},
 		outImplicitMX: false,
 	}, {
 		inDomainName:  "test-a.definbox.com",
-		outMXHosts:    []*net.MX{{"test-a.definbox.com", 1}},
+		outMXHosts:    []*net.MX{{Host: "test-a.definbox.com", Pref: 1}},
 		outImplicitMX: true,
 	}, {
 		inDomainName:  "test-cname.definbox.com",
-		outMXHosts:    []*net.MX{{"mxa.ninomail.com", 10}, {"mxb.ninomail.com", 10}},
+		outMXHosts:    []*net.MX{{Host: "mxa.ninomail.com", Pref: 10}, {Host: "mxb.ninomail.com", Pref: 10}},
 		outImplicitMX: false,
 	}, {
 		inDomainName:  "definbox.com",
-		outMXHosts:    []*net.MX{{"mxa.ninomail.com", 10}, {"mxb.ninomail.com", 10}},
+		outMXHosts:    []*net.MX{{Host: "mxa.ninomail.com", Pref: 10}, {Host: "mxb.ninomail.com", Pref: 10}},
 		outImplicitMX: false,
 	}, {
 		desc: "If an MX host returned by the resolver contains non ASCII " +
 			"characters then it is silently dropped from the returned list",
 		inDomainName:  "test-unicode.definbox.com",
-		outMXHosts:    []*net.MX{{"mxa.definbox.com", 1}, {"mxb.definbox.com", 3}},
+		outMXHosts:    []*net.MX{{Host: "mxa.definbox.com", Pref: 1}, {Host: "mxb.definbox.com", Pref: 3}},
 		outImplicitMX: false,
 	}, {
 		desc:          "Underscore is allowed in domain names",
 		inDomainName:  "test-underscore.definbox.com",
-		outMXHosts:    []*net.MX{{"foo_bar.definbox.com", 1}},
+		outMXHosts:    []*net.MX{{Host: "foo_bar.definbox.com", Pref: 1}},
 		outImplicitMX: false,
 	}, {
 		inDomainName:  "test-яндекс.definbox.com",
-		outMXHosts:    []*net.MX{{"xn--test---mofb0ab4b8camvcmn8gxd.definbox.com", 10}},
+		outMXHosts:    []*net.MX{{Host: "xn--test---mofb0ab4b8camvcmn8gxd.definbox.com", Pref: 10}},
 		outImplicitMX: false,
 	}, {
 		inDomainName:  "xn--test--xweh4bya7b6j.definbox.com",
-		outMXHosts:    []*net.MX{{"xn--test---mofb0ab4b8camvcmn8gxd.definbox.com", 10}},
+		outMXHosts:    []*net.MX{{Host: "xn--test---mofb0ab4b8camvcmn8gxd.definbox.com", Pref: 10}},
 		outImplicitMX: false,
 	}, {
 		inDomainName:  "test-mx-ipv4.definbox.com",
-		outMXHosts:    []*net.MX{{"34.150.176.225", 10}},
+		outMXHosts:    []*net.MX{{Host: "34.150.176.225", Pref: 10}},
 		outImplicitMX: false,
 	}, {
 		inDomainName:  "test-mx-ipv6.definbox.com",
-		outMXHosts:    []*net.MX{{"::ffff:2296:b0e1", 10}},
+		outMXHosts:    []*net.MX{{Host: "::ffff:2296:b0e1", Pref: 10}},
 		outImplicitMX: false,
 	}} {
 		t.Run(tc.inDomainName, func(t *testing.T) {