diff --git a/src/Exceptions/InvalidDateTimeClass.php b/src/Exceptions/InvalidDateTimeClass.php
new file mode 100644
index 0000000..726c9fb
--- /dev/null
+++ b/src/Exceptions/InvalidDateTimeClass.php
@@ -0,0 +1,11 @@
+<?php
+
+namespace Spatie\OpeningHours\Exceptions;
+
+class InvalidDateTimeClass extends Exception
+{
+    public static function forString(string $string): self
+    {
+        return new self("The string `{$string}` isn't a valid class implementing DateTimeInterface.");
+    }
+}
diff --git a/src/Helpers/DateTimeCopier.php b/src/Helpers/DateTimeCopier.php
index 1ac34cd..60e1e14 100644
--- a/src/Helpers/DateTimeCopier.php
+++ b/src/Helpers/DateTimeCopier.php
@@ -8,8 +8,7 @@
 trait DateTimeCopier
 {
     /**
-     * @param DateTimeInterface $date
-     *
+     * @param  DateTimeInterface  $date
      * @return \DateTime|\DateTimeImmutable
      */
     protected function copyDateTime(DateTimeInterface $date): DateTimeInterface
diff --git a/src/Helpers/DiffTrait.php b/src/Helpers/DiffTrait.php
index 0fca5e7..9b79a09 100644
--- a/src/Helpers/DiffTrait.php
+++ b/src/Helpers/DiffTrait.php
@@ -33,9 +33,8 @@ private function diffInSeconds(string $stateCheckMethod, string $nextDateMethod,
     /**
      * Return the amount of open time (number of seconds as a floating number) between 2 dates/times.
      *
-     * @param DateTimeInterface $startDate
-     * @param DateTimeInterface $endDate
-     *
+     * @param  DateTimeInterface  $startDate
+     * @param  DateTimeInterface  $endDate
      * @return float
      */
     public function diffInOpenSeconds(DateTimeInterface $startDate, DateTimeInterface $endDate): float
@@ -46,9 +45,8 @@ public function diffInOpenSeconds(DateTimeInterface $startDate, DateTimeInterfac
     /**
      * Return the amount of open time (number of minutes as a floating number) between 2 dates/times.
      *
-     * @param DateTimeInterface $startDate
-     * @param DateTimeInterface $endDate
-     *
+     * @param  DateTimeInterface  $startDate
+     * @param  DateTimeInterface  $endDate
      * @return float
      */
     public function diffInOpenMinutes(DateTimeInterface $startDate, DateTimeInterface $endDate): float
@@ -59,9 +57,8 @@ public function diffInOpenMinutes(DateTimeInterface $startDate, DateTimeInterfac
     /**
      * Return the amount of open time (number of hours as a floating number) between 2 dates/times.
      *
-     * @param DateTimeInterface $startDate
-     * @param DateTimeInterface $endDate
-     *
+     * @param  DateTimeInterface  $startDate
+     * @param  DateTimeInterface  $endDate
      * @return float
      */
     public function diffInOpenHours(DateTimeInterface $startDate, DateTimeInterface $endDate): float
@@ -72,9 +69,8 @@ public function diffInOpenHours(DateTimeInterface $startDate, DateTimeInterface
     /**
      * Return the amount of closed time (number of seconds as a floating number) between 2 dates/times.
      *
-     * @param DateTimeInterface $startDate
-     * @param DateTimeInterface $endDate
-     *
+     * @param  DateTimeInterface  $startDate
+     * @param  DateTimeInterface  $endDate
      * @return float
      */
     public function diffInClosedSeconds(DateTimeInterface $startDate, DateTimeInterface $endDate): float
@@ -85,9 +81,8 @@ public function diffInClosedSeconds(DateTimeInterface $startDate, DateTimeInterf
     /**
      * Return the amount of closed time (number of minutes as a floating number) between 2 dates/times.
      *
-     * @param DateTimeInterface $startDate
-     * @param DateTimeInterface $endDate
-     *
+     * @param  DateTimeInterface  $startDate
+     * @param  DateTimeInterface  $endDate
      * @return float
      */
     public function diffInClosedMinutes(DateTimeInterface $startDate, DateTimeInterface $endDate): float
@@ -98,9 +93,8 @@ public function diffInClosedMinutes(DateTimeInterface $startDate, DateTimeInterf
     /**
      * Return the amount of closed time (number of hours as a floating number) between 2 dates/times.
      *
-     * @param DateTimeInterface $startDate
-     * @param DateTimeInterface $endDate
-     *
+     * @param  DateTimeInterface  $startDate
+     * @param  DateTimeInterface  $endDate
      * @return float
      */
     public function diffInClosedHours(DateTimeInterface $startDate, DateTimeInterface $endDate): float
diff --git a/src/OpeningHours.php b/src/OpeningHours.php
index e729f41..3617f92 100644
--- a/src/OpeningHours.php
+++ b/src/OpeningHours.php
@@ -3,11 +3,13 @@
 namespace Spatie\OpeningHours;
 
 use DateTime;
+use DateTimeImmutable;
 use DateTimeInterface;
 use DateTimeZone;
 use Generator;
 use Spatie\OpeningHours\Exceptions\Exception;
 use Spatie\OpeningHours\Exceptions\InvalidDate;
+use Spatie\OpeningHours\Exceptions\InvalidDateTimeClass;
 use Spatie\OpeningHours\Exceptions\InvalidDayName;
 use Spatie\OpeningHours\Exceptions\InvalidTimezone;
 use Spatie\OpeningHours\Exceptions\MaximumLimitExceeded;
@@ -40,6 +42,9 @@ class OpeningHours
     /** @var int Number of days to try before abandoning the search of the next close/open time */
     protected $dayLimit = null;
 
+    /** @var string */
+    protected $dateTimeClass = DateTime::class;
+
     public function __construct($timezone = null)
     {
         if ($timezone instanceof DateTimeZone) {
@@ -56,9 +61,8 @@ public function __construct($timezone = null)
     }
 
     /**
-     * @param string[][]               $data
-     * @param string|DateTimeZone|null $timezone
-     *
+     * @param  string[][]  $data
+     * @param  string|DateTimeZone|null  $timezone
      * @return static
      */
     public static function create(array $data, $timezone = null): self
@@ -67,9 +71,8 @@ public static function create(array $data, $timezone = null): self
     }
 
     /**
-     * @param array $data         hours definition array or sub-array
-     * @param array $excludedKeys keys to ignore from parsing
-     *
+     * @param  array  $data  hours definition array or sub-array
+     * @param  array  $excludedKeys  keys to ignore from parsing
      * @return array
      */
     public static function mergeOverlappingRanges(array $data, array $excludedKeys = ['data', 'filters', 'overflow'])
@@ -116,9 +119,8 @@ public static function mergeOverlappingRanges(array $data, array $excludedKeys =
     }
 
     /**
-     * @param string[][]               $data
-     * @param string|DateTimeZone|null $timezone
-     *
+     * @param  string[][]  $data
+     * @param  string|DateTimeZone|null  $timezone
      * @return static
      */
     public static function createAndMergeOverlappingRanges(array $data, $timezone = null)
@@ -127,8 +129,7 @@ public static function createAndMergeOverlappingRanges(array $data, $timezone =
     }
 
     /**
-     * @param array $data
-     *
+     * @param  array  $data
      * @return bool
      */
     public static function isValid(array $data): bool
@@ -142,14 +143,36 @@ public static function isValid(array $data): bool
         }
     }
 
+    /**
+     * Select the class to use to create new date-time instances.
+     *
+     * @param  string|null  $dateTimeClass
+     * @return $this
+     *
+     * @throws InvalidDateTimeClass if $dateTimeClass is set with a string that is not a valid DateTimeInterface.
+     */
+    public function setDateTimeClass(string $dateTimeClass = null)
+    {
+        if ($dateTimeClass !== null && ! is_a($dateTimeClass, DateTimeInterface::class, true)) {
+            throw InvalidDateTimeClass::forString($dateTimeClass);
+        }
+
+        $this->dateTimeClass = $dateTimeClass ?? DateTime::class;
+
+        return $this;
+    }
+
     /**
      * Set the number of days to try before abandoning the search of the next close/open time.
      *
-     * @param int $dayLimit number of days
+     * @param  int  $dayLimit  number of days
+     * @return $this
      */
     public function setDayLimit(int $dayLimit)
     {
         $this->dayLimit = $dayLimit;
+
+        return $this;
     }
 
     /**
@@ -176,7 +199,8 @@ public function getFilters(): array
 
     public function fill(array $data)
     {
-        list($openingHours, $exceptions, $metaData, $filters, $overflow) = $this->parseOpeningHoursAndExceptions($data);
+        list($openingHours, $exceptions, $metaData, $filters, $overflow, $dateTimeClass) = $this
+            ->parseOpeningHoursAndExceptions($data);
 
         $this->overflow = $overflow;
 
@@ -186,7 +210,7 @@ public function fill(array $data)
 
         $this->setExceptionsFromStrings($exceptions);
 
-        return $this->setFilters($filters)->setData($metaData);
+        return $this->setDateTimeClass($dateTimeClass)->setFilters($filters)->setData($metaData);
     }
 
     public function forWeek(): array
@@ -261,8 +285,7 @@ public function forDate(DateTimeInterface $date): OpeningHoursForDay
     }
 
     /**
-     * @param DateTimeInterface $date
-     *
+     * @param  DateTimeInterface  $date
      * @return TimeRange[]
      */
     public function forDateTime(DateTimeInterface $date): array
@@ -286,7 +309,7 @@ public function isOpenOn(string $day): bool
             list(, $year, $month, $day) = $match;
             $year = $year ?: date('Y');
 
-            return count($this->forDate(new DateTime("$year-$month-$day", $this->timezone))) > 0;
+            return count($this->forDate(new DateTimeImmutable("$year-$month-$day", $this->timezone))) > 0;
         }
 
         return count($this->forDay($day)) > 0;
@@ -321,12 +344,12 @@ public function isClosedAt(DateTimeInterface $dateTime): bool
 
     public function isOpen(): bool
     {
-        return $this->isOpenAt(new DateTime());
+        return $this->isOpenAt(new $this->dateTimeClass());
     }
 
     public function isClosed(): bool
     {
-        return $this->isClosedAt(new DateTime());
+        return $this->isClosedAt(new $this->dateTimeClass());
     }
 
     public function currentOpenRange(DateTimeInterface $dateTime)
@@ -376,8 +399,9 @@ public function currentOpenRangeEnd(DateTimeInterface $dateTime)
         return $dateTime->setTime($nextDateTime->format('G'), $nextDateTime->format('i'), 0);
     }
 
-    public function nextOpen(DateTimeInterface $dateTime): DateTimeInterface
+    public function nextOpen(DateTimeInterface $dateTime = null): DateTimeInterface
     {
+        $dateTime = $dateTime ?? new $this->dateTimeClass();
         $dateTime = $this->copyDateTime($dateTime);
         $openingHoursForDay = $this->forDate($dateTime);
         $nextOpen = $openingHoursForDay->nextOpen(Time::fromDateTime($dateTime));
@@ -413,8 +437,9 @@ public function nextOpen(DateTimeInterface $dateTime): DateTimeInterface
         return $dateTime->setTime($nextDateTime->format('G'), $nextDateTime->format('i'), 0);
     }
 
-    public function nextClose(DateTimeInterface $dateTime): DateTimeInterface
+    public function nextClose(DateTimeInterface $dateTime = null): DateTimeInterface
     {
+        $dateTime = $dateTime ?? new $this->dateTimeClass();
         $dateTime = $this->copyDateTime($dateTime);
         $nextClose = null;
         if ($this->overflow) {
@@ -569,6 +594,7 @@ public function setTimezone($timezone)
 
     protected function parseOpeningHoursAndExceptions(array $data): array
     {
+        $dateTimeClass = Arr::pull($data, 'dateTimeClass', null);
         $metaData = Arr::pull($data, 'data', null);
         $exceptions = [];
         $filters = Arr::pull($data, 'filters', []);
@@ -590,7 +616,7 @@ protected function parseOpeningHoursAndExceptions(array $data): array
             $openingHours[$this->normalizeDayName($day)] = $openingHoursData;
         }
 
-        return [$openingHours, $exceptions, $metaData, $filters, $overflow];
+        return [$openingHours, $exceptions, $metaData, $filters, $overflow, $dateTimeClass];
     }
 
     protected function setOpeningHoursFromStrings(string $day, array $openingHours)
diff --git a/src/OpeningHoursForDay.php b/src/OpeningHoursForDay.php
index 9372ef3..e687e7d 100644
--- a/src/OpeningHoursForDay.php
+++ b/src/OpeningHoursForDay.php
@@ -71,9 +71,8 @@ public function isOpenAtNight(Time $time)
     }
 
     /**
-     * @param callable[] $filters
-     * @param bool       $reverse
-     *
+     * @param  callable[]  $filters
+     * @param  bool  $reverse
      * @return Time|bool
      */
     public function openingHoursFilter(array $filters, bool $reverse = false)
@@ -92,8 +91,7 @@ public function openingHoursFilter(array $filters, bool $reverse = false)
     }
 
     /**
-     * @param Time $time
-     *
+     * @param  Time  $time
      * @return bool|Time
      */
     public function nextOpen(Time $time)
@@ -106,8 +104,7 @@ function ($timeRange) use ($time) {
     }
 
     /**
-     * @param Time $time
-     *
+     * @param  Time  $time
      * @return bool|TimeRange
      */
     public function nextOpenRange(Time $time)
@@ -120,8 +117,7 @@ function ($timeRange) use ($time) {
     }
 
     /**
-     * @param Time $time
-     *
+     * @param  Time  $time
      * @return bool|Time
      */
     public function nextClose(Time $time)
@@ -137,8 +133,7 @@ function ($timeRange) use ($time) {
     }
 
     /**
-     * @param Time $time
-     *
+     * @param  Time  $time
      * @return bool|TimeRange
      */
     public function nextCloseRange(Time $time)
@@ -154,8 +149,7 @@ function ($timeRange) use ($time) {
     }
 
     /**
-     * @param Time $time
-     *
+     * @param  Time  $time
      * @return bool|Time
      */
     public function previousOpen(Time $time)
@@ -171,8 +165,7 @@ function ($timeRange) use ($time) {
     }
 
     /**
-     * @param Time $time
-     *
+     * @param  Time  $time
      * @return bool|TimeRange
      */
     public function previousOpenRange(Time $time)
@@ -185,8 +178,7 @@ function ($timeRange) use ($time) {
     }
 
     /**
-     * @param Time $time
-     *
+     * @param  Time  $time
      * @return bool|Time
      */
     public function previousClose(Time $time)
@@ -199,8 +191,7 @@ function ($timeRange) use ($time) {
     }
 
     /**
-     * @param Time $time
-     *
+     * @param  Time  $time
      * @return bool|TimeRange
      */
     public function previousCloseRange(Time $time)
@@ -251,8 +242,7 @@ public function getIterator()
     }
 
     /**
-     * @param Time $time
-     *
+     * @param  Time  $time
      * @return TimeRange[]
      */
     public function forTime(Time $time): Generator
@@ -267,8 +257,7 @@ public function forTime(Time $time): Generator
     }
 
     /**
-     * @param Time $time
-     *
+     * @param  Time  $time
      * @return TimeRange[]
      */
     public function forNightTime(Time $time): Generator
diff --git a/tests/OpeningHoursCustomClassTest.php b/tests/OpeningHoursCustomClassTest.php
new file mode 100644
index 0000000..3a9067c
--- /dev/null
+++ b/tests/OpeningHoursCustomClassTest.php
@@ -0,0 +1,74 @@
+<?php
+
+namespace Spatie\OpeningHours\Test;
+
+use DateTimeImmutable;
+use DateTimeZone;
+use PHPUnit\Framework\TestCase;
+use Spatie\OpeningHours\Exceptions\InvalidDateTimeClass;
+use Spatie\OpeningHours\OpeningHours;
+
+class OpeningHoursCustomClassTest extends TestCase
+{
+    protected function setUp()
+    {
+        date_default_timezone_set('UTC');
+    }
+
+    /** @test */
+    public function it_can_use_immutable_date_time()
+    {
+        $openingHours = OpeningHours::create([
+            'monday' => ['09:00-18:00'],
+            'dateTimeClass' => DateTimeImmutable::class,
+        ]);
+
+        $date = $openingHours->nextOpen(new DateTimeImmutable('2021-10-11 04:30'));
+
+        $this->assertInstanceOf(DateTimeImmutable::class, $date);
+        $this->assertSame('2021-10-11 09:00:00', $date->format('Y-m-d H:i:s'));
+    }
+
+    /** @test */
+    public function it_can_use_mocked_time()
+    {
+        $mock1 = new class extends DateTimeImmutable
+        {
+            public function __construct($datetime = 'now', DateTimeZone $timezone = null)
+            {
+                parent::__construct('2021-10-11 04:30', $timezone);
+            }
+        };
+        $mock2 = new class extends DateTimeImmutable
+        {
+            public function __construct($datetime = 'now', DateTimeZone $timezone = null)
+            {
+                parent::__construct('2021-10-11 09:30', $timezone);
+            }
+        };
+
+        $openingHours = OpeningHours::create([
+            'monday' => ['09:00-18:00'],
+            'dateTimeClass' => get_class($mock1),
+        ]);
+
+        $this->assertFalse($openingHours->isOpen());
+
+        $openingHours = OpeningHours::create([
+            'monday' => ['09:00-18:00'],
+            'dateTimeClass' => get_class($mock2),
+        ]);
+
+        $this->assertTrue($openingHours->isOpen());
+    }
+
+    /** @test */
+    public function it_should_refuse_invalid_date_time_class()
+    {
+        $this->expectException(InvalidDateTimeClass::class);
+        OpeningHours::create([
+            'monday' => ['09:00-18:00'],
+            'dateTimeClass' => DateTimeZone::class,
+        ]);
+    }
+}