diff --git a/LEGO1/omni/include/mxmusicmanager.h b/LEGO1/omni/include/mxmusicmanager.h
index 48c2df69..6deb88b3 100644
--- a/LEGO1/omni/include/mxmusicmanager.h
+++ b/LEGO1/omni/include/mxmusicmanager.h
@@ -27,7 +27,7 @@ class MxMusicManager : public MxAudioManager {
 
 	MxResult ResetStream();
 	void ResetBuffer();
-	undefined4 InitializeMIDI(MxU8* p_data, MxS32 p_loopCount);
+	MxResult InitializeMIDI(MxU8* p_data, MxS32 p_loopCount);
 	void DeinitializeMIDI();
 	void SetMultiplier(MxS32 p_multiplier);
 
diff --git a/LEGO1/omni/src/audio/mxmusicmanager.cpp b/LEGO1/omni/src/audio/mxmusicmanager.cpp
index b936ac30..3f2a4dd5 100644
--- a/LEGO1/omni/src/audio/mxmusicmanager.cpp
+++ b/LEGO1/omni/src/audio/mxmusicmanager.cpp
@@ -204,7 +204,7 @@ MxS32 MxMusicManager::CalculateVolume(MxS32 p_volume)
 }
 
 // FUNCTION: LEGO1 0x100c09c0
-undefined4 MxMusicManager::InitializeMIDI(MxU8* p_data, MxS32 p_loopCount)
+MxResult MxMusicManager::InitializeMIDI(MxU8* p_data, MxS32 p_loopCount)
 {
 	MxResult result = FAILURE;