diff --git a/index.js b/index.js
index 26cec8d..df6f300 100644
--- a/index.js
+++ b/index.js
@@ -116,6 +116,8 @@ function equal(a, b) {
     return true;
   }
 
+
+  // NaN verify
   return a !== a && b !== b;
 }
 // end fast-deep-equal