diff --git a/lib/index.js b/lib/index.js
index 40a2431..a55b620 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -24,6 +24,8 @@ var doCompare = function(f1, f2, cb, step, bufferSize) {
   assert(step <= bufferSize);
 
   if (f1.size !== f2.size) {
+    fs.closeSync(f1.fd);
+    fs.closeSync(f2.fd);
     return cb(false);
   }
   var isDone = false;