diff --git a/stepmania/src/RageSoundReader_MP3.cpp b/stepmania/src/RageSoundReader_MP3.cpp
index e7fc9d4a2b..6f6b23ecc9 100644
--- a/stepmania/src/RageSoundReader_MP3.cpp
+++ b/stepmania/src/RageSoundReader_MP3.cpp
@@ -601,11 +601,14 @@ SoundReader_FileReader::OpenResult RageSoundReader_MP3::Open( CString filename_
 	if(mad->bitrate == -1)
 		mad->bitrate = mad->Frame.header.bitrate;
 
+	SampleRate = mad->Frame.header.samplerate;
 	mad->framelength = mad->Frame.header.duration;
+	this->Channels = 0;
 
 	/* Since we've already decoded a frame, just synth it instead of rewinding
 	 * the stream. */
 	synth_output();
+	this->Channels = MAD_NCHANNELS( &mad->Frame.header );
 
     if(mad->length == -1)
     {
@@ -615,8 +618,6 @@ SoundReader_FileReader::OpenResult RageSoundReader_MP3::Open( CString filename_
 		mad->length = (int)(secs * 1000.f);
 	}
 
-	SampleRate = mad->Frame.header.samplerate;
-	this->Channels = mad->Frame.header.mode == MAD_MODE_SINGLE_CHANNEL? 1:2;
 	return OPEN_OK;
 }