diff --git a/tests/unit/Dict/MergeTest.php b/tests/unit/Dict/MergeTest.php
index 811fab18..7c8ae510 100644
--- a/tests/unit/Dict/MergeTest.php
+++ b/tests/unit/Dict/MergeTest.php
@@ -30,6 +30,16 @@ public function provideData(): array
                 ['d' => 'e'],
             ],
 
+            [
+                [0 => 'b', '1000' => 'b', 'c' => 'c'],
+
+                [0 => 'a'],
+                [0 => 'b'],
+                ['1000' => 'a'],
+                ['1000' => 'b'],
+                ['c' => 'c'],
+            ],
+
             [
                 [1, 2, 9, 8],
                 [0 => 1, 1 => 2],