diff --git a/app/internal/proxymux/manager_test.go b/app/internal/proxymux/manager_test.go
index 1d5a7af..c776058 100644
--- a/app/internal/proxymux/manager_test.go
+++ b/app/internal/proxymux/manager_test.go
@@ -31,9 +31,6 @@ func TestListenSOCKS(t *testing.T) {
 	}
 	sl.Close()
 
-	// Wait for muxListener.socksListener released
-	time.Sleep(time.Second)
-
 	sl, err = ListenSOCKS(address)
 	if !assert.NoError(t, err) {
 		return
@@ -63,9 +60,6 @@ func TestListenHTTP(t *testing.T) {
 	}
 	hl.Close()
 
-	// Wait for muxListener.socksListener released
-	time.Sleep(time.Second)
-
 	hl, err = ListenHTTP(address)
 	if !assert.NoError(t, err) {
 		return
diff --git a/app/internal/proxymux/mux_test.go b/app/internal/proxymux/mux_test.go
index 0e24f95..7a42b83 100644
--- a/app/internal/proxymux/mux_test.go
+++ b/app/internal/proxymux/mux_test.go
@@ -1,7 +1,9 @@
 package proxymux
 
 import (
+	"bytes"
 	"net"
+	"sync"
 	"testing"
 	"time"
 
@@ -13,25 +15,52 @@ import (
 
 //go:generate mockery
 
-func testMockListener(t *testing.T, firstByte byte) net.Listener {
-	mockConn := mocks.NewMockConn(t)
-	mockConn.EXPECT().Read(mock.Anything).RunAndReturn(func(b []byte) (int, error) {
-		b[0] = firstByte
-		return 1, nil
-	})
-	mockConn.EXPECT().Close().Return(nil)
+func testMockListener(t *testing.T, connChan <-chan net.Conn) net.Listener {
+	closedChan := make(chan struct{})
 	mockListener := mocks.NewMockListener(t)
 	mockListener.EXPECT().Accept().RunAndReturn(func() (net.Conn, error) {
-		// Wait for all listener set up
-		time.Sleep(200 * time.Millisecond)
-		return mockConn, nil
+		select {
+		case <-closedChan:
+			return nil, net.ErrClosed
+		case conn, ok := <-connChan:
+			if !ok {
+				panic("unexpected closed channel (connChan)")
+			}
+			return conn, nil
+		}
+	})
+	mockListener.EXPECT().Close().RunAndReturn(func() error {
+		select {
+		case <-closedChan:
+		default:
+			close(closedChan)
+		}
+		return nil
 	})
-	mockListener.EXPECT().Close().Return(nil)
 	return mockListener
 }
 
+func testMockConn(t *testing.T, b []byte) net.Conn {
+	buf := bytes.NewReader(b)
+	isClosed := false
+	mockConn := mocks.NewMockConn(t)
+	mockConn.EXPECT().Read(mock.Anything).RunAndReturn(func(b []byte) (int, error) {
+		if isClosed {
+			return 0, net.ErrClosed
+		}
+		return buf.Read(b)
+	})
+	mockConn.EXPECT().Close().RunAndReturn(func() error {
+		isClosed = true
+		return nil
+	})
+	return mockConn
+}
+
 func TestMuxHTTP(t *testing.T) {
-	mockListener := testMockListener(t, 'C')
+	connChan := make(chan net.Conn)
+	mockListener := testMockListener(t, connChan)
+	mockConn := testMockConn(t, []byte("CONNECT example.com:443 HTTP/1.1\r\n\r\n"))
 
 	mux := newMuxListener(mockListener, func() {})
 	hl, err := mux.ListenHTTP()
@@ -43,22 +72,28 @@ func TestMuxHTTP(t *testing.T) {
 		return
 	}
 
+	connChan <- mockConn
+
 	var socksConn, httpConn net.Conn
 	var socksErr, httpErr error
 
+	var wg sync.WaitGroup
+	wg.Add(2)
 	go func() {
 		socksConn, socksErr = sl.Accept()
+		wg.Done()
 	}()
-
 	go func() {
 		httpConn, httpErr = hl.Accept()
+		wg.Done()
 	}()
 
-	time.Sleep(1 * time.Second)
+	time.Sleep(time.Second)
+
 	sl.Close()
 	hl.Close()
-	// Wait for unmatched handler error
-	time.Sleep(1 * time.Second)
+
+	wg.Wait()
 
 	assert.Nil(t, socksConn)
 	assert.ErrorIs(t, socksErr, net.ErrClosed)
@@ -67,11 +102,13 @@ func TestMuxHTTP(t *testing.T) {
 	assert.NoError(t, httpErr)
 
 	// Wait for muxListener released
-	time.Sleep(time.Second)
+	<-mux.acceptChan
 }
 
 func TestMuxSOCKS(t *testing.T) {
-	mockListener := testMockListener(t, '\x05')
+	connChan := make(chan net.Conn)
+	mockListener := testMockListener(t, connChan)
+	mockConn := testMockConn(t, []byte{0x05, 0x02, 0x00, 0x01}) // SOCKS5 Connect Request: NOAUTH+GSSAPI
 
 	mux := newMuxListener(mockListener, func() {})
 	hl, err := mux.ListenHTTP()
@@ -83,22 +120,28 @@ func TestMuxSOCKS(t *testing.T) {
 		return
 	}
 
+	connChan <- mockConn
+
 	var socksConn, httpConn net.Conn
 	var socksErr, httpErr error
 
+	var wg sync.WaitGroup
+	wg.Add(2)
 	go func() {
 		socksConn, socksErr = sl.Accept()
+		wg.Done()
 	}()
-
 	go func() {
 		httpConn, httpErr = hl.Accept()
+		wg.Done()
 	}()
 
-	time.Sleep(1 * time.Second)
+	time.Sleep(time.Second)
+
 	sl.Close()
 	hl.Close()
-	// Wait for unmatched handler error
-	time.Sleep(1 * time.Second)
+
+	wg.Wait()
 
 	assert.NotNil(t, socksConn)
 	socksConn.Close()
@@ -107,5 +150,5 @@ func TestMuxSOCKS(t *testing.T) {
 	assert.ErrorIs(t, httpErr, net.ErrClosed)
 
 	// Wait for muxListener released
-	time.Sleep(time.Second)
+	<-mux.acceptChan
 }