diff --git a/modules/juce_audio_processors/utilities/juce_ExtensionsVisitor.h b/modules/juce_audio_processors/utilities/juce_ExtensionsVisitor.h
index dcf0ff8f6..f497fef96 100644
--- a/modules/juce_audio_processors/utilities/juce_ExtensionsVisitor.h
+++ b/modules/juce_audio_processors/utilities/juce_ExtensionsVisitor.h
@@ -63,7 +63,9 @@ typedef AudioComponentInstance AudioUnit;
     }
     @endcode
 */
+#ifndef _VESTIGE_H
 struct AEffect;
+#endif
 
 //==============================================================================
 namespace juce