diff --git a/database/socket/database.go b/database/socket/database.go
index 3a0f9fd..c5e6083 100644
--- a/database/socket/database.go
+++ b/database/socket/database.go
@@ -8,6 +8,7 @@ package socket
 import (
 	"log"
 	"net"
+	"sync"
 	"time"
 
 	"github.com/FreifunkBremen/yanic/database"
@@ -16,8 +17,9 @@ import (
 
 type Connection struct {
 	database.Connection
-	listener net.Listener
-	clients  map[net.Addr]net.Conn
+	listener  net.Listener
+	clients   map[net.Addr]net.Conn
+	clientMux sync.Mutex
 }
 
 func init() {
@@ -56,8 +58,10 @@ func (conn *Connection) PruneNodes(deleteAfter time.Duration) {
 }
 
 func (conn *Connection) Close() {
+	conn.clientMux.Lock()
 	for _, c := range conn.clients {
 		c.Close()
 	}
+	conn.clientMux.Unlock()
 	conn.listener.Close()
 }
diff --git a/database/socket/internal.go b/database/socket/internal.go
index 662dc8d..311ce2d 100644
--- a/database/socket/internal.go
+++ b/database/socket/internal.go
@@ -11,18 +11,21 @@ type EventMessage struct {
 	Body  interface{} `json:"body,omitempty"`
 }
 
-func (config *Connection) handleSocketConnection(ln net.Listener) {
+func (conn *Connection) handleSocketConnection(ln net.Listener) {
 	for {
 		c, err := ln.Accept()
 		if err != nil {
 			log.Println("[socket-database] error during connection of a client", err)
 			continue
 		}
-		config.clients[c.RemoteAddr()] = c
+		conn.clientMux.Lock()
+		conn.clients[c.RemoteAddr()] = c
+		conn.clientMux.Unlock()
 	}
 }
 
 func (conn *Connection) sendJSON(msg EventMessage) {
+	conn.clientMux.Lock()
 	for addr, c := range conn.clients {
 		d := json.NewEncoder(c)
 
@@ -33,4 +36,5 @@ func (conn *Connection) sendJSON(msg EventMessage) {
 			delete(conn.clients, addr)
 		}
 	}
+	conn.clientMux.Unlock()
 }