diff --git a/lemarche/siaes/models.py b/lemarche/siaes/models.py
index 05ff2ef4d..e625b653c 100644
--- a/lemarche/siaes/models.py
+++ b/lemarche/siaes/models.py
@@ -1262,7 +1262,17 @@ def clean(self):
         Does not use a unique constraint on model because it allows blank values and checks two fields simultaneously.
         """
         super().clean()
+
+        # Check only if brand is set and different from the original brand
+        # (to avoid validation error on update without brand change)
+        check_brand_uniqueness = False
         if self.brand:
+            check_brand_uniqueness = True
+            if self.pk:
+                original_brand = Siae.objects.get(pk=self.pk).brand
+                check_brand_uniqueness = original_brand != self.brand
+
+        if check_brand_uniqueness:
             # Check if brand is used as name by another Siae
             name_exists = Siae.objects.exclude(id=self.id).filter(Q(name=self.brand) | Q(brand=self.brand)).exists()
             if name_exists:
diff --git a/lemarche/siaes/tests/test_models.py b/lemarche/siaes/tests/test_models.py
index fb2fe0eaa..ea6b5fc94 100644
--- a/lemarche/siaes/tests/test_models.py
+++ b/lemarche/siaes/tests/test_models.py
@@ -1,3 +1,4 @@
+from django.core.exceptions import ValidationError
 from django.test import TestCase
 from django.utils import timezone
 
@@ -418,6 +419,45 @@ def test_set_super_badge(self):
         self.assertTrue(siae_super_badge_2.super_badge)
         self.assertEqual(siae_super_badge_2.super_badge_last_updated, siae_super_badge_last_updated_current_value)
 
+    def test_brand_uniqueness(self):
+        SiaeFactory(name="Name 1", brand="Brand 1")
+        SiaeFactory(brand="Brand 2")
+        siae_3 = SiaeFactory(brand="Brand 1")
+        self.assertEqual(Siae.objects.filter(brand="Brand 1").count(), 2)
+
+        # can update something else than brand
+        siae_3.contact_first_name = "Contact 1"
+        siae_3.clean()
+        siae_3.save()
+
+        self.assertEqual(Siae.objects.filter(brand="Brand 1").count(), 2)
+        siae_3.refresh_from_db()
+        self.assertEqual(siae_3.contact_first_name, "Contact 1")
+
+        # can't update brand to an existing brand
+        siae_3.brand = "Brand 2"
+        with self.assertRaises(ValidationError):
+            siae_3.clean()
+            siae_3.save()
+        self.assertEqual(Siae.objects.filter(brand="Brand 1").count(), 2)
+
+        # can't update brand to an existing name
+        siae_3.brand = "Name 1"
+        with self.assertRaises(ValidationError):
+            siae_3.clean()
+            siae_3.save()
+
+        siae_3.refresh_from_db()
+        self.assertEqual(siae_3.brand, "Brand 1")
+
+        # can update brand to a non existing brand
+        siae_3.brand = "Brand 3"
+        siae_3.name = "Name 3"
+        siae_3.clean()
+        siae_3.save()
+        siae_3.refresh_from_db()
+        self.assertEqual(siae_3.brand, "Brand 3")
+
 
 class SiaeModelQuerysetTest(TestCase):
     @classmethod