diff --git a/index.js b/index.js
index 85b5ac0..d965f5b 100755
--- a/index.js
+++ b/index.js
@@ -459,4 +459,7 @@ PNGImage.instrument = function () {
 	};
 };
 
+PNGImage.Decoder = Decoder;
+PNGImage.Encoder = Encoder;
+
 module.exports = PNGImage;