diff --git a/Command/ListCommand.php b/Command/ListCommand.php
index 340c205..a72bbbc 100644
--- a/Command/ListCommand.php
+++ b/Command/ListCommand.php
@@ -60,7 +60,7 @@ protected function execute(InputInterface $input, OutputInterface $output): int
             $row = [($id + 1), get_class($task)];
 
             if ($showRunDates) {
-                $nextRunDates = $task->getNextRunDates($numberOfRunDates);
+                $nextRunDates = $task->getNextRunDates(intval($numberOfRunDates));
                 $row[] = implode(', ', $nextRunDates);
             }
 
diff --git a/Tests/Command/ListCommandTest.php b/Tests/Command/ListCommandTest.php
index f0c6707..8d3e482 100644
--- a/Tests/Command/ListCommandTest.php
+++ b/Tests/Command/ListCommandTest.php
@@ -72,4 +72,32 @@ public function testListCommandWithOption(): void
             $output
         );
     }
+
+    public function testListCommandWithStringOption(): void
+    {
+        $container = $this->loadContainer();
+        $scheduler = $container->get('ts.scheduler');
+        $scheduler->addTask(new TaskMock());
+
+        $application = new Application();
+        /** @var Scheduler $scheduler */
+        $application->add(new ListCommand($scheduler));
+
+        $command = $application->find('ts:list');
+
+        $runDates = random_int(2, 32);
+
+        $commandTester = new CommandTester($command);
+        $commandTester->execute([
+            'command' => $command->getName(),
+            '--show-run-dates' => (string) $runDates,
+        ]);
+
+        $output = $commandTester->getDisplay();
+        $this->assertStringContainsString($runDates . ' run dates', $output);
+        $this->assertStringContainsString(
+            '| 1  | Rewieer\TaskSchedulerBundle\Tests\TaskMock | nextRunDate, anotherRunDate',
+            $output
+        );
+    }
 }