diff --git a/pkg/pmapi/dialer_proxy.go b/pkg/pmapi/dialer_proxy.go
index 137fbca3..f39ea86a 100644
--- a/pkg/pmapi/dialer_proxy.go
+++ b/pkg/pmapi/dialer_proxy.go
@@ -60,11 +60,16 @@ func formatAsAddress(rawURL string) string {
 		panic(err)
 	}
 
+	host := url.Host
+	if host == "" {
+		host = url.Path
+	}
+
 	port := "443"
 	if url.Scheme == "http" {
 		port = "80"
 	}
-	return net.JoinHostPort(url.Host, port)
+	return net.JoinHostPort(host, port)
 }
 
 // DialTLS dials the given network/address. If it fails, it retries using a proxy.
diff --git a/pkg/pmapi/dialer_proxy_provider.go b/pkg/pmapi/dialer_proxy_provider.go
index 6cedef8a..1526bf2d 100644
--- a/pkg/pmapi/dialer_proxy_provider.go
+++ b/pkg/pmapi/dialer_proxy_provider.go
@@ -36,11 +36,16 @@ const (
 	proxyDoHTimeout          = 20 * time.Second
 	proxyCanReachTimeout     = 20 * time.Second
 	proxyQuery               = "dMFYGSLTQOJXXI33ONVQWS3BOMNUA.protonpro.xyz"
+
+	Quad9Provider     = "https://dns11.quad9.net/dns-query"
+	Quad9PortProvider = "https://dns11.quad9.net:5053/dns-query"
+	GoogleProvider    = "https://dns.google/dns-query"
 )
 
 var dohProviders = []string{ //nolint[gochecknoglobals]
-	"https://dns11.quad9.net/dns-query",
-	"https://dns.google/dns-query",
+	Quad9Provider,
+	Quad9PortProvider,
+	GoogleProvider,
 }
 
 // proxyProvider manages known proxies.
diff --git a/pkg/pmapi/dialer_proxy_provider_test.go b/pkg/pmapi/dialer_proxy_provider_test.go
index a036f401..4fca808d 100644
--- a/pkg/pmapi/dialer_proxy_provider_test.go
+++ b/pkg/pmapi/dialer_proxy_provider_test.go
@@ -27,12 +27,6 @@ import (
 	"golang.org/x/net/http/httpproxy"
 )
 
-const (
-	TestDoHQuery       = "dMFYGSLTQOJXXI33ONVQWS3BOMNUA.protonpro.xyz"
-	TestQuad9Provider  = "https://dns11.quad9.net/dns-query"
-	TestGoogleProvider = "https://dns.google/dns-query"
-)
-
 func TestProxyProvider_FindProxy(t *testing.T) {
 	proxy := getTrustedServer()
 	defer closeServer(proxy)
@@ -142,17 +136,28 @@ func TestProxyProvider_FindProxy_CanReachTimeout(t *testing.T) {
 }
 
 func TestProxyProvider_DoHLookup_Quad9(t *testing.T) {
-	p := newProxyProvider(Config{}, []string{TestQuad9Provider, TestGoogleProvider}, TestDoHQuery)
+	p := newProxyProvider(Config{}, []string{Quad9Provider, GoogleProvider}, proxyQuery)
 
-	records, err := p.dohLookup(context.Background(), TestDoHQuery, TestQuad9Provider)
+	records, err := p.dohLookup(context.Background(), proxyQuery, Quad9Provider)
+	r.NoError(t, err)
+	r.NotEmpty(t, records)
+}
+
+// DISABLEDTestProxyProvider_DoHLookup_Quad9Port cannot run on CI due to custom
+// port filter. Basic functionality should be covered by other tests. Keeping
+// code here to be able to run it locally if needed.
+func DISABLEDTestProxyProviderDoHLookupQuad9Port(t *testing.T) {
+	p := newProxyProvider(Config{}, []string{Quad9PortProvider, GoogleProvider}, proxyQuery)
+
+	records, err := p.dohLookup(context.Background(), proxyQuery, Quad9PortProvider)
 	r.NoError(t, err)
 	r.NotEmpty(t, records)
 }
 
 func TestProxyProvider_DoHLookup_Google(t *testing.T) {
-	p := newProxyProvider(Config{}, []string{TestQuad9Provider, TestGoogleProvider}, TestDoHQuery)
+	p := newProxyProvider(Config{}, []string{Quad9Provider, GoogleProvider}, proxyQuery)
 
-	records, err := p.dohLookup(context.Background(), TestDoHQuery, TestGoogleProvider)
+	records, err := p.dohLookup(context.Background(), proxyQuery, GoogleProvider)
 	r.NoError(t, err)
 	r.NotEmpty(t, records)
 }
@@ -160,7 +165,7 @@ func TestProxyProvider_DoHLookup_Google(t *testing.T) {
 func TestProxyProvider_DoHLookup_FindProxy(t *testing.T) {
 	skipIfProxyIsSet(t)
 
-	p := newProxyProvider(Config{}, []string{TestQuad9Provider, TestGoogleProvider}, TestDoHQuery)
+	p := newProxyProvider(Config{}, []string{Quad9Provider, GoogleProvider}, proxyQuery)
 
 	url, err := p.findReachableServer()
 	r.NoError(t, err)
@@ -170,7 +175,7 @@ func TestProxyProvider_DoHLookup_FindProxy(t *testing.T) {
 func TestProxyProvider_DoHLookup_FindProxyFirstProviderUnreachable(t *testing.T) {
 	skipIfProxyIsSet(t)
 
-	p := newProxyProvider(Config{}, []string{"https://unreachable", TestQuad9Provider, TestGoogleProvider}, TestDoHQuery)
+	p := newProxyProvider(Config{}, []string{"https://unreachable", Quad9Provider, GoogleProvider}, proxyQuery)
 
 	url, err := p.findReachableServer()
 	r.NoError(t, err)
diff --git a/pkg/pmapi/dialer_proxy_test.go b/pkg/pmapi/dialer_proxy_test.go
index aef64576..039a13ff 100644
--- a/pkg/pmapi/dialer_proxy_test.go
+++ b/pkg/pmapi/dialer_proxy_test.go
@@ -251,3 +251,18 @@ func TestProxyDialer_UseProxy_FindSecondAlternativeIfFirstFailsAndAPIIsStillBloc
 	require.NoError(t, err)
 	require.Equal(t, formatAsAddress(proxy2.URL), d.proxyAddress)
 }
+
+func TestFormatAsAddress(t *testing.T) {
+	r := require.New(t)
+	testData := map[string]string{
+		"sub.domain.tld":         "sub.domain.tld:443",
+		"http://sub.domain.tld":  "sub.domain.tld:80",
+		"https://sub.domain.tld": "sub.domain.tld:443",
+		"ftp://sub.domain.tld":   "sub.domain.tld:443",
+		"//sub.domain.tld":       "sub.domain.tld:443",
+	}
+
+	for rawURL, wantURL := range testData {
+		r.Equal(wantURL, formatAsAddress(rawURL))
+	}
+}