diff --git a/modules/juce_audio_basics/mpe/juce_MPESynthesiser.h b/modules/juce_audio_basics/mpe/juce_MPESynthesiser.h
index 408970e6c5..7c266a7b76 100644
--- a/modules/juce_audio_basics/mpe/juce_MPESynthesiser.h
+++ b/modules/juce_audio_basics/mpe/juce_MPESynthesiser.h
@@ -297,11 +297,11 @@ protected:
 
     //==============================================================================
     OwnedArray<MPESynthesiserVoice> voices;
+    CriticalSection voicesLock;
 
 private:
     //==============================================================================
     bool shouldStealVoices;
-    CriticalSection voicesLock;
 
     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (MPESynthesiser)
 };