diff --git a/.phpunit.result.cache b/.phpunit.result.cache
deleted file mode 100644
index 471bc86..0000000
--- a/.phpunit.result.cache
+++ /dev/null
@@ -1 +0,0 @@
-{"version":1,"defects":[],"times":{"strftimeTest::test_sum":0.056,"strftimeTest::test_ymdhms":0.006}}
\ No newline at end of file
diff --git a/composer.json b/composer.json
index 368637e..07cbb95 100644
--- a/composer.json
+++ b/composer.json
@@ -1,6 +1,6 @@
 {
   "name": "php81_bc/strftime",
-  "version": "0.0.5",
+  "version": "0.0.6",
   "description": "Locale-formatted strftime using IntlDateFormatter (PHP 8.1 compatible)",
   "license": "MIT",
   "authors": [
diff --git a/phpunit.xml b/phpunit.xml
index 0fe1d02..5ce6b41 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit bootstrap="vendor/autoload.php" colors="true">
+<phpunit bootstrap="vendor/autoload.php" colors="true" cacheResultFile="tmp/phpunit.cache">
     <testsuite name="Test directory">
         <directory>tests</directory>
     </testsuite>
diff --git a/tests/strftimeTest.php b/tests/strftimeTest.php
index 38fa6a0..ed7ae9b 100644
--- a/tests/strftimeTest.php
+++ b/tests/strftimeTest.php
@@ -10,10 +10,18 @@ public function setUp () : void {
       $this->int_date = strtotime($this->str_date);
     }
 
-    public function test_ymdhms () {
-        $result = strftime('%Y-%m-%d %H:%M:%S', $this->str_date);
-        $this->assertEquals('2022-03-12 01:02:03', $result);
-        $result = strftime('%Y-%m-%d %H:%M:%S', $this->int_date);
-        $this->assertEquals('2022-03-12 01:02:03', $result);
+    public function test_int_timestamp () {
+      $result = strftime('%Y-%m-%d %H:%M:%S', $this->int_date);
+      $this->assertEquals('2022-03-12 01:02:03', $result);
+    }
+
+    public function test_string_timestamp () {
+      $result = strftime('%Y-%m-%d %H:%M:%S', $this->str_date);
+      $this->assertEquals('2022-03-12 01:02:03', $result);
+    }
+
+    public function test_datetime_timestamp () {
+      $result = strftime('%Y-%m-%d %H:%M:%S', new DateTime($this->str_date));
+      $this->assertEquals('2022-03-12 01:02:03', $result);
     }
   }