diff --git a/pdm/builders/api.py b/pdm/builders/api.py
index 59588c8eb3e05ac766f12a6711ef26484a447bf3..440c7f552e9606ace93e2d6a1d04a276cea8b3b5 100644
--- a/pdm/builders/api.py
+++ b/pdm/builders/api.py
@@ -29,7 +29,7 @@ def prepare_metadata_for_build_wheel(metadata_directory, config_settings=None):
     builder = WheelBuilder(ireq)
 
     dist_info = Path(metadata_directory, builder.dist_info_name)
-    dist_info.makedirs(exist_ok=True)
+    dist_info.mkdir(exist_ok=True)
     with builder:
         if builder.meta.entry_points:
             with (dist_info / "entry_points.txt").open("w", encoding="utf-8") as f:
@@ -41,7 +41,7 @@ def prepare_metadata_for_build_wheel(metadata_directory, config_settings=None):
         with (dist_info / "METADATA").open("w", encoding="utf-8") as f:
             builder._write_metadata_file(f)
 
-        return dist_info.name
+    return dist_info.name
 
 
 def build_wheel(wheel_directory, config_settings=None, metadata_directory=None):
diff --git a/pdm/cli/actions.py b/pdm/cli/actions.py
index 8b54a28be2452d3ab39ae08ef30b9f77312127f6..8a71daf94af14523cb7755693bdae502b8e6cb4a 100644
--- a/pdm/cli/actions.py
+++ b/pdm/cli/actions.py
@@ -335,7 +335,7 @@ def do_init(
                 "dev-dependencies": tomlkit.table(),
             }
         },
-        "build-system": {"requires": "pdm", "build-backend": "pdm.builders.api"},
+        "build-system": {"requires": ["pdm"], "build-backend": "pdm.builders.api"},
     }
     if not project.pyproject:
         project._pyproject = data