diff --git a/spec/Collection/TasksCollectionSpec.php b/spec/Collection/TasksCollectionSpec.php
index 6edcabbec..db1974e6f 100644
--- a/spec/Collection/TasksCollectionSpec.php
+++ b/spec/Collection/TasksCollectionSpec.php
@@ -68,7 +68,20 @@ function it_can_filter_by_task_names(TaskInterface $task1, TaskInterface $task2)
         $task2->getName()->willReturn('task2');
         $tasks = ['task1'];
 
-        $result = $this->filterByTaskName($tasks);
+        $result = $this->filterByTaskNames($tasks);
+        $result->shouldBeAnInstanceOf(TasksCollection::class);
+        $result->count()->shouldBe(1);
+        $tasks = $result->toArray();
+        $tasks[0]->shouldBe($task1);
+    }
+
+    function it_can_filter_by_duplicate_task_names(TaskInterface $task1, TaskInterface $task2)
+    {
+        $task1->getName()->willReturn('task1');
+        $task2->getName()->willReturn('task2');
+        $tasks = ['task1', 'task1'];
+
+        $result = $this->filterByTaskNames($tasks);
         $result->shouldBeAnInstanceOf(TasksCollection::class);
         $result->count()->shouldBe(1);
         $tasks = $result->toArray();
@@ -81,7 +94,7 @@ function it_can_filter_by_empty_task_names(TaskInterface $task1, TaskInterface $
         $task2->getName()->willReturn('task2');
         $tasks = [];
 
-        $result = $this->filterByTaskName($tasks);
+        $result = $this->filterByTaskNames($tasks);
         $result->shouldBeAnInstanceOf(TasksCollection::class);
         $result->count()->shouldBe(2);
         $tasks = $result->toArray();
diff --git a/spec/Runner/TaskRunnerContextSpec.php b/spec/Runner/TaskRunnerContextSpec.php
index 53024a401..94eb94c46 100644
--- a/spec/Runner/TaskRunnerContextSpec.php
+++ b/spec/Runner/TaskRunnerContextSpec.php
@@ -11,7 +11,7 @@ class TaskRunnerContextSpec extends ObjectBehavior
 {
     function let(ContextInterface $context, TestSuiteInterface $testSuite)
     {
-        $this->beConstructedWith($context, $testSuite);
+        $this->beConstructedWith($context, [], $testSuite);
     }
 
     function it_is_initializable()
@@ -32,7 +32,7 @@ function it_has_a_test_suite(TestSuiteInterface $testSuite)
 
     function it_has_no_test_suite(ContextInterface $context)
     {
-        $this->beConstructedWith($context);
+        $this->beConstructedWith($context, []);
         $this->hasTestSuite()->shouldBe(false);
         $this->getTestSuite()->shouldBe(null);
     }
@@ -46,7 +46,7 @@ function it_has_no_tasks()
     function it_has_tasks(ContextInterface $context)
     {
         $tasks = ["task_1"];
-        $this->beConstructedWith($context, null, $tasks);
+        $this->beConstructedWith($context, $tasks);
         $this->hasTasks()->shouldBe(true);
         $this->getTasks()->shouldBe($tasks);
     }
diff --git a/src/Collection/TasksCollection.php b/src/Collection/TasksCollection.php
index e1ad8e9d0..1676a6bf6 100644
--- a/src/Collection/TasksCollection.php
+++ b/src/Collection/TasksCollection.php
@@ -36,16 +36,15 @@ public function filterByTestSuite(TestSuiteInterface $testSuite = null): self
 
     /**
      * @param string[] $tasks
-     *
-     * @return TasksCollection
      */
-    public function filterByTaskName($tasks)
+    public function filterByTaskNames($tasks): self
     {
+        if (empty($tasks)) {
+            return new self($this->toArray());
+        }
+
         return $this->filter(function (TaskInterface $task) use ($tasks) {
-            if (empty($tasks)) {
-                return true;
-            }
-            return in_array($task->getName(), $tasks);
+            return \in_array($task->getName(), $tasks, true);
         });
     }
 
@@ -54,7 +53,7 @@ public function filterByTaskName($tasks)
      */
     public function sortByPriority(GrumPHP $grumPHP): self
     {
-        $priorityQueue = new SplPriorityQueue();
+        $priorityQueue   = new SplPriorityQueue();
         $stableSortIndex = PHP_INT_MAX;
         foreach ($this->getIterator() as $task) {
             $metadata = $grumPHP->getTaskMetadata($task->getName());
diff --git a/src/Console/Command/RunCommand.php b/src/Console/Command/RunCommand.php
index cd6cb9191..43639ba42 100644
--- a/src/Console/Command/RunCommand.php
+++ b/src/Console/Command/RunCommand.php
@@ -68,12 +68,12 @@ public function execute(InputInterface $input, OutputInterface $output)
         $files = $this->getRegisteredFiles();
         $testSuites = $this->grumPHP->getTestSuites();
 
-        $tasks = $this->parseCommaSeparatedOption($input->getOption("tasks"));
+        $tasks = $this->parseCommaSeparatedOption($input->getOption("tasks") ?? "");
 
         $context = new TaskRunnerContext(
             new RunContext($files),
-            (bool) $input->getOption('testsuite') ? $testSuites->getRequired($input->getOption('testsuite')) : null,
-            $tasks
+            $tasks,
+            (bool) $input->getOption('testsuite') ? $testSuites->getRequired($input->getOption('testsuite')) : null
         );
 
         return $this->taskRunner()->run($output, $context);
@@ -101,7 +101,7 @@ protected function paths(): PathsHelper
      * @param string $value
      * @return string[]
      */
-    protected function parseCommaSeparatedOption($value)
+    protected function parseCommaSeparatedOption(string $value)
     {
         $stringValues = explode(",", $value);
         $parsedValues = [];
@@ -110,7 +110,7 @@ protected function parseCommaSeparatedOption($value)
             if (empty($v)) {
                 continue;
             }
-            $parsedValues[$v] = $v;
+            $parsedValues[] = $v;
         }
         return $parsedValues;
     }
diff --git a/src/Runner/TaskRunner.php b/src/Runner/TaskRunner.php
index bdde516f4..99c773e11 100644
--- a/src/Runner/TaskRunner.php
+++ b/src/Runner/TaskRunner.php
@@ -69,7 +69,7 @@ public function run(TaskRunnerContext $runnerContext): TaskResultCollection
         $tasks = $this->tasks
             ->filterByContext($runnerContext->getTaskContext())
             ->filterByTestSuite($runnerContext->getTestSuite())
-            ->filterByTaskName($runnerContext->getTasks())
+            ->filterByTaskNames($runnerContext->getTasks())
             ->sortByPriority($this->grumPHP);
         $taskResults = new TaskResultCollection();
 
diff --git a/test/Console/Command/RunCommandTest.php b/test/Console/Command/RunCommandTest.php
index 1f9ad4d03..5b4d62778 100644
--- a/test/Console/Command/RunCommandTest.php
+++ b/test/Console/Command/RunCommandTest.php
@@ -2,36 +2,32 @@
 
 namespace GrumPHPTest\Console\Command;
 
-use GrumPHP\Configuration\GrumPHP;
 use GrumPHP\Console\Command\RunCommand;
-use GrumPHP\Locator\RegisteredFiles;
 use PHPUnit\Framework\TestCase;
 
 class RunCommandTest extends TestCase
 {
     /**
      * @test
-     * @param null $valueString
-     * @param null $expected
+     * @param string $valueString
+     * @param array $expected
      * @dataProvider parses_comma_separated_options_dataProvider
-     * @throws \ReflectionException
      */
-    function parses_comma_separated_options($valueString = null, $expected = null)
+    function parses_comma_separated_options(string $valueString, array $expected)
     {
-        /**
-         * @var GrumPHP $grumPhp
-         */
-        $grumPhp = $this->createMock(GrumPHP::class);
-        /**
-         * @var RegisteredFiles $registeredFiles
-         */
-        $registeredFiles = $this->createMock(RegisteredFiles::class);
+        $command = new class extends RunCommand{
+            public function __construct()
+            {
+            }
 
-        $command = new RunCommand($grumPhp, $registeredFiles);
-        $method  = new \ReflectionMethod($command, "parseCommaSeparatedOption");
-        $method->setAccessible(true);
+            public function parseCommaSeparatedOption($str)
+            {
+                return parent::parseCommaSeparatedOption(... func_get_args());
+            }
+        };
 
-        $actual = $method->invoke($command, $valueString);
+        $actual = $command->parseCommaSeparatedOption($valueString);
+        $actual = array_values($actual);
 
         $this->assertEquals($expected, $actual);
     }
@@ -43,28 +39,17 @@ public function parses_comma_separated_options_dataProvider()
             "default" => [
                 "valueString"  => "foo,bar",
                 "expected"  => [
-                    "foo" => "foo",
-                    "bar" => "bar"
+                    "foo",
+                    "bar"
                 ],
             ],
             "trims values" => [
                 "valueString"  => "foo , bar",
                 "expected"  => [
-                    "foo" => "foo",
-                    "bar" => "bar"
+                    "foo",
+                    "bar"
                 ],
             ],
-            "deduplicates values" => [
-                "valueString"  => "foo,bar,bar",
-                "expected"  => [
-                    "foo" => "foo",
-                    "bar" => "bar"
-                ],
-            ],
-            "null" => [
-                "valueString"  => null,
-                "expected"  => [],
-            ],
             "empty" => [
                 "valueString"  => "",
                 "expected"  => [],