diff --git a/src/TaskManager.php b/src/TaskManager.php
index 4df81d8..4ab73ae 100644
--- a/src/TaskManager.php
+++ b/src/TaskManager.php
@@ -21,6 +21,8 @@ use JMS\Serializer\SerializerBuilder;
  */
 class TaskManager
 {
+    const PATTERN = '/^[\wäüö]*$/i';
+
     /**
      * @var Taskwarrior
      */
@@ -216,6 +218,16 @@ class TaskManager
             $errors[] = "A recurring task must also have a 'due' date.";
         }
 
+        if (!preg_match(static::PATTERN, $task->getProject())) {
+            $errors[] = sprintf("Project with the name '%s' is not allowed", $task->getProject());
+        }
+
+        foreach ($task->getTags() as $tag) {
+            if (!preg_match(static::PATTERN, $tag)) {
+                $errors[] = sprintf("Tag with the name '%s' is not allowed", $tag);
+            }
+        }
+
         return $errors;
     }
 
diff --git a/tests/TaskManagerTest.php b/tests/TaskManagerTest.php
index eca749d..740770a 100644
--- a/tests/TaskManagerTest.php
+++ b/tests/TaskManagerTest.php
@@ -549,6 +549,18 @@ class TaskManagerTest extends \PHPUnit_Framework_TestCase
         $this->assertCount(1,$this->taskManager->filterPending('+später'));
     }
 
+    public function testTagNameNotAllowed()
+    {
+        $this->setExpectedException('DavidBadura\Taskwarrior\Exception\TaskwarriorException',
+            "Tag with the name 'foo-bar' is not allowed");
+
+        $task1 = new Task();
+        $task1->setDescription('foo1');
+        $task1->addTag('foo-bar');
+
+        $this->taskManager->save($task1);
+    }
+
     public function testWait()
     {
         $task1 = new Task();