diff --git a/dnsforward/dnsforward_test.go b/dnsforward/dnsforward_test.go
index 430d2f35..341f2fad 100644
--- a/dnsforward/dnsforward_test.go
+++ b/dnsforward/dnsforward_test.go
@@ -249,6 +249,39 @@ func TestBlockedRequest(t *testing.T) {
 	}
 }
 
+func TestServerCustomClientUpstream(t *testing.T) {
+	s := createTestServer(t)
+	err := s.Start()
+	if err != nil {
+		t.Fatalf("Failed to start server: %s", err)
+	}
+	s.conf.GetCustomUpstreamByClient = func(clientAddr string) *proxy.UpstreamConfig {
+		uc := &proxy.UpstreamConfig{}
+		u := &testUpstream{}
+		u.ipv4 = map[string][]net.IP{}
+		u.ipv4["host."] = []net.IP{net.ParseIP("192.168.0.1")}
+		uc.Upstreams = append(uc.Upstreams, u)
+		return uc
+	}
+	addr := s.dnsProxy.Addr(proxy.ProtoUDP)
+
+	// Send test request
+	req := dns.Msg{}
+	req.Id = dns.Id()
+	req.RecursionDesired = true
+	req.Question = []dns.Question{
+		{Name: "host.", Qtype: dns.TypeA, Qclass: dns.ClassINET},
+	}
+
+	reply, err := dns.Exchange(&req, addr.String())
+
+	assert.Nil(t, err)
+	assert.Equal(t, dns.RcodeSuccess, reply.Rcode)
+	assert.NotNil(t, reply.Answer)
+	assert.Equal(t, "192.168.0.1", reply.Answer[0].(*dns.A).A.String())
+	assert.Nil(t, s.Stop())
+}
+
 // testUpstream is a mock of real upstream.
 // specify fields with necessary values to simulate real upstream behaviour
 type testUpstream struct {
diff --git a/dnsforward/helpers.go b/dnsforward/helpers.go
deleted file mode 100644
index e7212355..00000000
--- a/dnsforward/helpers.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package dnsforward
-
-import "net"
-
-// GetIPString is a helper function that extracts IP address from net.Addr
-func GetIPString(addr net.Addr) string {
-	switch addr := addr.(type) {
-	case *net.UDPAddr:
-		return addr.IP.String()
-	case *net.TCPAddr:
-		return addr.IP.String()
-	}
-	return ""
-}
diff --git a/dnsforward/util.go b/dnsforward/util.go
index f5c62cb8..f159f43a 100644
--- a/dnsforward/util.go
+++ b/dnsforward/util.go
@@ -8,6 +8,17 @@ import (
 	"github.com/AdguardTeam/golibs/utils"
 )
 
+// GetIPString is a helper function that extracts IP address from net.Addr
+func GetIPString(addr net.Addr) string {
+	switch addr := addr.(type) {
+	case *net.UDPAddr:
+		return addr.IP.String()
+	case *net.TCPAddr:
+		return addr.IP.String()
+	}
+	return ""
+}
+
 func stringArrayDup(a []string) []string {
 	a2 := make([]string, len(a))
 	copy(a2, a)