diff --git a/lib/session.js b/lib/session.js
index 8f5f64beb2..98ca1d24df 100644
--- a/lib/session.js
+++ b/lib/session.js
@@ -59,7 +59,7 @@ function storeData (input, data) {
     let val = input[i]
 
     // Delete values when users unselect checkboxes
-    if (val === '_unchecked' || val === ['_unchecked']) {
+    if ([val].flat().every((item) => item === '_unchecked')) {
       delete data[i]
       continue
     }
diff --git a/lib/session.test.js b/lib/session.test.js
index ca851c6a7a..feacb8483e 100644
--- a/lib/session.test.js
+++ b/lib/session.test.js
@@ -89,7 +89,7 @@ describe('autoStoreData', () => {
     }
     const expectedData = {
       checkBoxes1: ['cb1-1', 'cb1-2'],
-      checkBoxes2: [],
+      checkBoxes2: undefined,
       checkBoxes3: ['cb3-1', 'cb3-2'],
       existingData: 'existing data'
     }