diff --git a/lib/index.js b/lib/index.js
index 40a2431..1c56903 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;
@@ -81,6 +83,11 @@ var doCompare = function(f1, f2, cb, step, bufferSize) {
     fs.closeSync(f1.fd);
     fs.closeSync(f2.fd);
     return cb(false);
+  })
+  .catch((reason) => {
+    fs.closeSync(f1.fd);
+    fs.closeSync(f2.fd);
+    return Promise.reject(reason);
   });
 };