diff --git a/esp32/lib/ESP32-sveltekit/EventSocket.cpp b/esp32/lib/ESP32-sveltekit/EventSocket.cpp
index 3c8d335..b3cc737 100644
--- a/esp32/lib/ESP32-sveltekit/EventSocket.cpp
+++ b/esp32/lib/ESP32-sveltekit/EventSocket.cpp
@@ -61,9 +61,11 @@ void EventSocket::onWSOpen(PsychicWebSocketClient *client) {
 }
 
 void EventSocket::onWSClose(PsychicWebSocketClient *client) {
+    xSemaphoreTake(clientSubscriptionsMutex, portMAX_DELAY);
     for (auto &event_subscriptions : client_subscriptions) {
         event_subscriptions.second.remove(client->socket());
     }
+    xSemaphoreGive(clientSubscriptionsMutex);
     ESP_LOGI("EventSocket", "ws[%s][%u] disconnect", client->remoteIP().toString().c_str(), client->socket());
 }