diff --git a/webapp/models.py b/webapp/models.py
index 4638cab..856d00a 100644
--- a/webapp/models.py
+++ b/webapp/models.py
@@ -20,7 +20,7 @@ VERBOSE_NAME = _('Webapp')
 class Tag(models.Model):
     """Model for tag."""
 
-    slug = models.SlugField(primary_key=True)
+    slug = models.SlugField(unique=True)
     name = models.CharField(max_length=127)
     icon = models.ImageField()