diff --git a/src/audiomixerboard.cpp b/src/audiomixerboard.cpp
index 20c823bf2f..08c45b2310 100644
--- a/src/audiomixerboard.cpp
+++ b/src/audiomixerboard.cpp
@@ -1349,9 +1349,12 @@ void CAudioMixerBoard::ApplyNewConClientList ( CVector<CChannelInfo>& vecChanInf
 
         for ( size_t iFader = 0; iFader < iNumConnectedClients; iFader++ )
         {
-            // ideally "iChanID" in CChannelInfo would be size_t if it can never be INVALID_INDEX
-            // as assumed here
-            iFaderNumber[vecChanInfo[iFader].iChanID] = static_cast<int> ( iFader );
+            const int iChanID = vecChanInfo[iFader].iChanID;
+
+            if ( MathUtils::InRange<int> ( iChanID, 0, MAX_NUM_CHANNELS ) )
+            {
+                iFaderNumber[iChanID] = static_cast<int> ( iFader );
+            }
         }
 
         // Hide all unused faders and initialize used ones
diff --git a/src/util.h b/src/util.h
index b083cd42a5..026aa6e768 100644
--- a/src/util.h
+++ b/src/util.h
@@ -1222,6 +1222,13 @@ class MathUtils
             return powf ( 10.0f, ( fInValueRange0_1 - 1.0f ) * AUD_MIX_FADER_RANGE_DB / 20.0f );
         }
     }
+
+    // Returns true if value is in [lower, upper) (inclusive lower, exclusive upper).
+    template<typename T>
+    static inline bool InRange ( T value, T lower /* inclusive */, T upper /* exclusive */ )
+    {
+        return value >= lower && value < upper;
+    }
 };
 
 /******************************************************************************\