diff --git a/conn.go b/conn.go
index 0ef03905c6..6adb94618e 100644
--- a/conn.go
+++ b/conn.go
@@ -172,8 +172,7 @@ func (c *connect) settings(querySettings Settings) []proto.Setting {
 }
 
 func (c *connect) isBad() bool {
-	switch {
-	case c.closed:
+	if c.isClosed() {
 		return true
 	}
 
@@ -188,6 +187,20 @@ func (c *connect) isBad() bool {
 	return false
 }
 
+func (c *connect) isClosed() bool {
+	c.mutexClose.Lock()
+	defer c.mutexClose.Unlock()
+
+	return c.closed
+}
+
+func (c *connect) setClosed() {
+	c.mutexClose.Lock()
+	defer c.mutexClose.Unlock()
+
+	c.closed = true
+}
+
 func (c *connect) close() error {
 	c.mutexClose.Lock()
 	if c.closed {
@@ -198,7 +211,11 @@ func (c *connect) close() error {
 	c.mutexClose.Unlock()
 
 	c.buffer = nil
+
+	c.mutex.Lock()
 	c.reader = nil
+	c.mutex.Unlock()
+
 	if err := c.conn.Close(); err != nil {
 		return err
 	}
@@ -238,7 +255,7 @@ func (c *connect) compressBuffer(start int) error {
 }
 
 func (c *connect) sendData(block *proto.Block, name string) error {
-	if c.closed {
+	if c.isClosed() {
 		err := errors.New("attempted sending on closed connection")
 		c.debugf("[send data] err: %v", err)
 		return err
@@ -284,10 +301,10 @@ func (c *connect) sendData(block *proto.Block, name string) error {
 		switch {
 		case errors.Is(err, syscall.EPIPE):
 			c.debugf("[send data] pipe is broken, closing connection")
-			c.closed = true
+			c.setClosed()
 		case errors.Is(err, io.EOF):
 			c.debugf("[send data] unexpected EOF, closing connection")
-			c.closed = true
+			c.setClosed()
 		default:
 			c.debugf("[send data] unexpected error: %v", err)
 		}
@@ -302,7 +319,7 @@ func (c *connect) sendData(block *proto.Block, name string) error {
 }
 
 func (c *connect) readData(ctx context.Context, packet byte, compressible bool) (*proto.Block, error) {
-	if c.closed {
+	if c.isClosed() {
 		err := errors.New("attempted reading on closed connection")
 		c.debugf("[read data] err: %v", err)
 		return nil, err