diff --git a/src/client.cpp b/src/client.cpp
index 9b5e502bee..0ba02b41e2 100644
--- a/src/client.cpp
+++ b/src/client.cpp
@@ -505,6 +505,8 @@ void CClient::SetDoAutoSockBufSize ( const bool bValue )
 
 void CClient::SetRemoteChanGain ( const int iId, const float fGain, const bool bIsMyOwnFader )
 {
+    Q_ASSERT ( iId >= 0 && iId < MAX_NUM_CHANNELS );
+
     QMutexLocker locker ( &MutexGainOrPan );
 
     CClientChannel* clientChan = &clientChannels[iId];
diff --git a/src/protocol.cpp b/src/protocol.cpp
index 3030c2dca1..200104a1bb 100644
--- a/src/protocol.cpp
+++ b/src/protocol.cpp
@@ -1056,6 +1056,11 @@ bool CProtocol::EvaluateClientIDMes ( const CVector<uint8_t>& vecData )
     // channel ID
     const int iCurID = static_cast<int> ( GetValFromStream ( vecData, iPos, 1 ) );
 
+    if ( iCurID >= MAX_NUM_CHANNELS )
+    {
+        return true; // return error code
+    }
+
     // invoke message action
     emit ClientIDReceived ( iCurID );