diff --git a/cmMidi.h b/cmMidi.h
index ec3dbb9..b6f4859 100644
--- a/cmMidi.h
+++ b/cmMidi.h
@@ -89,7 +89,7 @@ extern "C" {
 #define cmMidiIsChStatus( s ) (kNoteOffMdId <= (s) && (s) <  kSysExMdId)
 
 #define cmMidiIsNoteOn( s )      ( kNoteOnMdId <= (s) && (s) <= (kNoteOnMdId + kMidiChCnt) )
-#define cmMidiIsNoteOff( s, d1 ) ( cmMidiIsNoteOn(s) && (d1)==0 || kNoteOffMdId <= (s) && (s) <= (kNoteOffMdId + kMidiChCnt) )
+#define cmMidiIsNoteOff( s, d1 ) ( (cmMidiIsNoteOn(s) && (d1)==0) || (kNoteOffMdId <= (s) && (s) <= (kNoteOffMdId + kMidiChCnt)) )
 #define cmMidiIsCtl( s )         ( kCtlMdId <= (s) && (s) <= (kCtlMdId + kMidiChCnt) )
 
 #define cmMidiIsSustainPedal(     s, d0 )    ( kCtlMdId <= (s) && (s) <= (kCtlMdId + kMidiChCnt) && (d0)== kSustainCtlMdId )