diff --git a/modules/juce_audio_processors/processors/juce_AudioProcessorGraph.cpp b/modules/juce_audio_processors/processors/juce_AudioProcessorGraph.cpp
index 23c2086e6d..2d4c97c53b 100644
--- a/modules/juce_audio_processors/processors/juce_AudioProcessorGraph.cpp
+++ b/modules/juce_audio_processors/processors/juce_AudioProcessorGraph.cpp
@@ -919,6 +919,7 @@ private:
 
         void processWithBuffer (const GlobalIO&, bool bypass, AudioBuffer<FloatType>& audio, MidiBuffer& midi) final
         {
+            const ScopedLock lock { this->processor.getCallbackLock() };
             callProcess (bypass, audio, midi);
         }