diff --git a/db_mutex/migrations/0001_initial.py b/db_mutex/migrations/0001_initial.py
index 0b913fc..88607b5 100644
--- a/db_mutex/migrations/0001_initial.py
+++ b/db_mutex/migrations/0001_initial.py
@@ -14,7 +14,7 @@ class Migration(migrations.Migration):
             name='DBMutex',
             fields=[
                 ('id', models.AutoField(serialize=False, auto_created=True, verbose_name='ID', primary_key=True)),
-                ('lock_id', models.CharField(unique=True, max_length=256)),
+                ('lock_id', models.CharField(unique=True, max_length=255)),
                 ('creation_time', models.DateTimeField(auto_now_add=True)),
             ],
             options={
diff --git a/db_mutex/models.py b/db_mutex/models.py
index 100fd89..47e2705 100644
--- a/db_mutex/models.py
+++ b/db_mutex/models.py
@@ -6,12 +6,12 @@ class DBMutex(models.Model):
     Models a mutex lock with a ``lock_id`` and a ``creation_time``.
 
     :type lock_id: str
-    :param lock_id: A unique CharField with a max length of 256
+    :param lock_id: A unique CharField with a max length of 255
 
     :type creation_time: datetime
     :param creation_time: The creation time of the mutex lock
     """
-    lock_id = models.CharField(max_length=256, unique=True)
+    lock_id = models.CharField(max_length=255, unique=True)
     creation_time = models.DateTimeField(auto_now_add=True)
 
     class Meta: