diff --git a/modules/juce_audio_formats/codecs/juce_CoreAudioFormat.cpp b/modules/juce_audio_formats/codecs/juce_CoreAudioFormat.cpp
index f4a55920e1..d5bc42349e 100644
--- a/modules/juce_audio_formats/codecs/juce_CoreAudioFormat.cpp
+++ b/modules/juce_audio_formats/codecs/juce_CoreAudioFormat.cpp
@@ -132,7 +132,7 @@ struct CoreAudioFormatMetatdata
         const int64 originalPosition = input.getPosition();
 
         MemoryBlock midiBlock;
-        input.readIntoMemoryBlock (midiBlock, size);
+        input.readIntoMemoryBlock (midiBlock, (ssize_t) size);
         MemoryInputStream midiInputStream (midiBlock, false);
 
         StringPairArray midiMetadata;