diff --git a/zgw_consumers/migrations/0022_set_default_service_slug.py b/zgw_consumers/migrations/0022_set_default_service_slug.py
index aba6c9b..95fba02 100644
--- a/zgw_consumers/migrations/0022_set_default_service_slug.py
+++ b/zgw_consumers/migrations/0022_set_default_service_slug.py
@@ -16,6 +16,9 @@ def generate_unique_slug(original_slug, count=0):
 
     for row in Service.objects.all():
         candidate_slug = slugify(row.label if row.label else row.api_root)
+        if len(candidate_slug) > 254:
+            candidate_slug = candidate_slug[:250]
+
         row.slug = generate_unique_slug(candidate_slug)
         row.save(update_fields=["slug"])
 
@@ -34,6 +37,7 @@ class Migration(migrations.Migration):
                 unique=False,
                 blank=True,
                 db_index=False,
+                max_length=255,
             ),
             preserve_default=False,
         ),
diff --git a/zgw_consumers/models/services.py b/zgw_consumers/models/services.py
index 641914a..1f2f130 100644
--- a/zgw_consumers/models/services.py
+++ b/zgw_consumers/models/services.py
@@ -44,6 +44,7 @@ class Service(RestAPIService):
         help_text=_(
             "A unique, human-friendly slug to identify this service. Primarily useful for cross-instance import/export."
         ),
+        max_length=255,
     )
     api_type = models.CharField(_("type"), max_length=20, choices=APITypes.choices)
     api_root = models.CharField(_("api root url"), max_length=255, unique=True)