diff --git a/application/symfony/src/Attribut/SlugAttribut.php b/application/symfony/src/Attribut/SlugAttribut.php
index 40e658b..a17e839 100644
--- a/application/symfony/src/Attribut/SlugAttribut.php
+++ b/application/symfony/src/Attribut/SlugAttribut.php
@@ -2,6 +2,8 @@
 
 namespace App\Attribut;
 
+use App\Exception\UnvalidValueException;
+
 /**
  * @author kevinfrantz
  */
@@ -12,16 +14,30 @@ trait SlugAttribut
      */
     protected $slug;
 
+    /**
+     * @param string $slug
+     *
+     * @throws UnvalidValueException
+     */
     public function setSlug(string $slug): void
     {
+        if (is_numeric($slug)) {
+            throw new UnvalidValueException('A slug must not be numeric!');
+        }
         $this->slug = $slug;
     }
 
+    /**
+     * @return string
+     */
     public function getSlug(): string
     {
         return $this->slug;
     }
 
+    /**
+     * @return bool
+     */
     public function hasSlug(): bool
     {
         return isset($this->slug);
diff --git a/application/symfony/src/Exception/UnvalidValueException.php b/application/symfony/src/Exception/UnvalidValueException.php
new file mode 100644
index 0000000..91ce284
--- /dev/null
+++ b/application/symfony/src/Exception/UnvalidValueException.php
@@ -0,0 +1,10 @@
+<?php
+
+namespace App\Exception;
+
+/**
+ * @author kevinfrantz
+ */
+class UnvalidValueException extends \Exception
+{
+}
diff --git a/application/symfony/tests/Unit/Attribut/SlugAttributTest.php b/application/symfony/tests/Unit/Attribut/SlugAttributTest.php
index 6b8b4a1..cc51378 100644
--- a/application/symfony/tests/Unit/Attribut/SlugAttributTest.php
+++ b/application/symfony/tests/Unit/Attribut/SlugAttributTest.php
@@ -5,6 +5,7 @@ namespace Tests\Attribut;
 use PHPUnit\Framework\TestCase;
 use App\Attribut\SlugAttributInterface;
 use App\Attribut\SlugAttribut;
+use App\Exception\UnvalidValueException;
 
 /**
  * @author kevinfrantz
@@ -39,4 +40,10 @@ class SlugAttributTest extends TestCase
         $this->assertNull($this->slugAttribut->setSlug(''));
         $this->assertTrue($this->slugAttribut->hasSlug());
     }
+
+    public function testNumericSetException(): void
+    {
+        $this->expectException(UnvalidValueException::class);
+        $this->slugAttribut->setSlug('1234');
+    }
 }