diff --git a/stepmania/src/InputMapper.h b/stepmania/src/InputMapper.h
index 7f545f111b..09db9c4a4f 100644
--- a/stepmania/src/InputMapper.h
+++ b/stepmania/src/InputMapper.h
@@ -32,7 +32,7 @@ struct AutoMappingEntry
 
 	int m_iSlotIndex;
 	DeviceButton m_deviceButton;
-	GameButton m_gb; // GameButton_Invalid == end marker
+	GameButton m_gb; // GameButton_Invalid means unmap this button
 	/*
 	 * If this is true, this is an auxilliary mapping assigned to the second
 	 * player.  If two of the same device are found, and the device has secondary