diff --git a/core/modules/user/user.api.php b/core/modules/user/user.api.php
index 752d3d412d7..dc16906470d 100644
--- a/core/modules/user/user.api.php
+++ b/core/modules/user/user.api.php
@@ -243,9 +243,10 @@ function hook_user_operations() {
  * @see hook_user_update()
  */
 function hook_user_presave(&$edit, $account) {
-  // Make sure that our form value 'mymodule_foo' is stored as 'mymodule_bar'.
+  // Make sure that our form value 'mymodule_foo' is stored as
+  // 'mymodule_bar' in the 'data' (serialized) column.
   if (isset($edit['mymodule_foo'])) {
-    $edit['data']['my_module_foo'] = $edit['my_module_foo'];
+    $edit['data']['mymodule_bar'] = $edit['mymodule_foo'];
   }
 }