diff --git a/lib/buffer.js b/lib/buffer.js
index 25ab22b5c93..e20b3d5eb5a 100644
--- a/lib/buffer.js
+++ b/lib/buffer.js
@@ -156,6 +156,7 @@ function Buffer (subject, encoding, offset) {
   SlowBuffer.makeFastBuffer(this.parent, this, this.offset, this.length);
 }
 
+exports.SlowBuffer = SlowBuffer;
 exports.Buffer = Buffer;
 
 Buffer.poolSize = 8*1024;