diff --git a/src/Concealer.php b/src/Concealer.php
index e0385dc..d795053 100644
--- a/src/Concealer.php
+++ b/src/Concealer.php
@@ -48,7 +48,7 @@ public function conceal($input, array $keys = [])
     private function handleCollection($input)
     {
         $output = $input->map(function ($item, $key) {
-            if (in_array($key, $this->keys) === true) {
+            if (in_array($key, $this->keys, true) === true) {
                 return $input[$key] = '********';
             }
 
@@ -75,7 +75,7 @@ private function handleCollection($input)
     private function handleArray($input)
     {
         foreach ($input as $key => $item) {
-            if (in_array($key, $this->keys) === true) {
+            if (in_array($key, $this->keys, true) === true) {
                 $input[$key] = '********';
                 continue;
             }
diff --git a/tests/ConcealerTest.php b/tests/ConcealerTest.php
index a497f86..2b47f58 100644
--- a/tests/ConcealerTest.php
+++ b/tests/ConcealerTest.php
@@ -199,13 +199,25 @@ public function it_handles_numeric_keys_for_collections(): void
             'password' => new Collection([
                 'test',
                 'secret',
-            ])
+            ]),
+            'test' => new Collection([
+                'test',
+                'secret',
+            ]),
+            'test2' => [
+                'test',
+                'secret',
+            ]
         ]);
 
         $output = $this->concealer->conceal($data);
 
         $this->assertEquals('wouter', $output['username']);
         $this->assertEquals('********', $output['password']);
+        $this->assertEquals('test', $output['test'][0]);
+        $this->assertEquals('secret', $output['test'][1]);
+        $this->assertEquals('test', $output['test2'][0]);
+        $this->assertEquals('secret', $output['test2'][1]);
     }
 
     /** @test */