diff --git a/brand_external_report_layout/models/res_brand.py b/brand_external_report_layout/models/res_brand.py
index e559a5dfb..a609c08a6 100644
--- a/brand_external_report_layout/models/res_brand.py
+++ b/brand_external_report_layout/models/res_brand.py
@@ -103,6 +103,10 @@ def _get_asset_style_b64(self):
             {"brand_ids": self.sudo().search([])},
             raise_if_not_found=False,
         )
+        # An empty attachment cannot be read by the assets compiler,
+        # which breaks the report assets when there is no brand yet.
+        if not brand_styles.strip():
+            brand_styles = "/* No brand-specific styles configured */"
         return base64.b64encode(brand_styles.encode())
 
     def _update_asset_style(self):
diff --git a/brand_external_report_layout/tests/test_brand_external_report_layout.py b/brand_external_report_layout/tests/test_brand_external_report_layout.py
index 74b2edae2..61919d452 100644
--- a/brand_external_report_layout/tests/test_brand_external_report_layout.py
+++ b/brand_external_report_layout/tests/test_brand_external_report_layout.py
@@ -187,3 +187,8 @@ def test_brand_document_layout_get_asset_style(self):
         )
         result = wizard._get_asset_style()
         self.assertIsInstance(result, markupsafe.Markup)
+
+    def test_asset_style_not_empty_without_brand(self):
+        self.env["res.brand"].search([]).unlink()
+        content = base64.b64decode(self.env["res.brand"]._get_asset_style_b64())
+        self.assertTrue(content.strip())