diff --git a/snapcraft/internal/meta.py b/snapcraft/internal/meta.py
index d6b18b2c..bfa69b45 100644
--- a/snapcraft/internal/meta.py
+++ b/snapcraft/internal/meta.py
@@ -157,7 +157,8 @@ class _SnapPackaging:
             annotated_snapcraft = self._annotate_snapcraft(
                 copy.deepcopy(self._config_data))
             with open(manifest_file_path, 'w') as manifest_file:
-                yaml.dump(annotated_snapcraft, manifest_file)
+                yaml.dump(annotated_snapcraft, manifest_file,
+                          default_flow_style=False)
 
     def _annotate_snapcraft(self, data):
         for field in ('build-packages', 'build-snaps'):