diff --git a/src/utils/is-equal.js b/src/utils/is-equal.js
index a397031..1c47cdd 100644
--- a/src/utils/is-equal.js
+++ b/src/utils/is-equal.js
@@ -1,6 +1,6 @@
 const isEqual = (a, b) => {
   Object.keys(a).forEach(key => {
-    if (b[key] === undefined) {
+    if (typeof b[key] === 'undefined') {
       return false
     }