diff --git a/lib/jsmidgen.js b/lib/jsmidgen.js
index 742222a..84fa25f 100644
--- a/lib/jsmidgen.js
+++ b/lib/jsmidgen.js
@@ -434,7 +434,7 @@ var Midi = {};
 			type: MidiEvent.NOTE_ON,
 			channel: channel,
 			param1: Util.ensureMidiPitch(pitch),
-			param2: velocity || DEFAULT_VOLUME,
+			param2: velocity !== undefined && typeof velocity === 'number' ? velocity : DEFAULT_VOLUME,
 			time: time || 0,
 		}));
 		return this;
@@ -457,7 +457,7 @@ var Midi = {};
 			type: MidiEvent.NOTE_OFF,
 			channel: channel,
 			param1: Util.ensureMidiPitch(pitch),
-			param2: velocity || DEFAULT_VOLUME,
+			param2: velocity !== undefined && typeof velocity === 'number' ? velocity : DEFAULT_VOLUME,
 			time: time || 0,
 		}));
 		return this;