diff --git a/src/AP_WS_Server.cpp b/src/AP_WS_Server.cpp
index 8ae0022b..05febf46 100644
--- a/src/AP_WS_Server.cpp
+++ b/src/AP_WS_Server.cpp
@@ -341,6 +341,7 @@ namespace OpenWifi {
 					if(SerialNumbersMutex_[i].try_lock()) {
 						wait=0;
 						NumberOfConnectedDevices_ += SerialNumbers_[i].size();
+						SerialNumbersMutex_[i].unlock();
 					} else if (wait<5) {
 						++wait;
 						Poco::Thread::sleep(10);