diff --git a/cwMidi.h b/cwMidi.h
index 73887c4..adbe3ec 100644
--- a/cwMidi.h
+++ b/cwMidi.h
@@ -162,7 +162,7 @@ namespace cw
     uint8_t    sciPitchToMidi( const char* sciPitchStr );
 
     
-#define midi_to_hz( midi_pitch ) (13.75 * std::pow(2,(-9.0/12.0))) * std::pow(2.0,(midi_pitch / 12.0))
+#define midi_to_hz( midi_pitch ) ((13.75 * std::pow(2,(-9.0/12.0))) * std::pow(2.0,(midi_pitch / 12.0)))
 
 
   }