diff --git a/server/common_test.go b/server/common_test.go
deleted file mode 100644
index 47ad606..0000000
--- a/server/common_test.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package server
-
-import (
-	"testing"
-	"fmt"
-)
-
-func TestGo1(t *testing.T) {
-	ch := make(chan struct{},1000)
-	ch<-struct{}{}
-	fmt.Println(len(ch))
-	<-ch
-	fmt.Println(len(ch))
-}
diff --git a/server/server.go b/server/server.go
index e65741a..3d33ec5 100644
--- a/server/server.go
+++ b/server/server.go
@@ -617,11 +617,14 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 
 // Close immediately closes all active net.Listeners.
 func (s *Server) Close() error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
 	s.closeDoneChanLocked()
 	var err error
 	if s.ln != nil {
 		err = s.ln.Close()
 	}
+
 	for c := range s.activeConn {
 		c.Close()
 		delete(s.activeConn, c)