diff --git a/fretwork/midi/MidiFileParser.py b/fretwork/midi/MidiFileParser.py
index 1df64f9..f5ce334 100644
--- a/fretwork/midi/MidiFileParser.py
+++ b/fretwork/midi/MidiFileParser.py
@@ -39,7 +39,7 @@ def parseMThdChunk(self):
         header_chunk_zise = raw_in.readBew(4)
 
         # check if it is a proper midi file
-        if header_chunk_type != 'MThd':
+        if header_chunk_type != b'MThd':
             raise TypeError("It is not a valid midi file!")
 
         # Header values are at fixed locations, so no reason to be clever