diff --git a/lib/config.py b/lib/config.py
index f052d59..c8dc2c9 100644
--- a/lib/config.py
+++ b/lib/config.py
@@ -15,7 +15,7 @@ def config(filename="database.ini", section="production"):
             db[param[0]] = param[1]
     else:
         raise Exception(
-            "Section {0} not found in the {1} file".format(section, filename)
+            f"Section {section} not found in the {filename} file"
         )
 
     return db
diff --git a/lib/db_revision.py b/lib/db_revision.py
index 0723ee8..cdc246f 100644
--- a/lib/db_revision.py
+++ b/lib/db_revision.py
@@ -255,7 +255,7 @@ class DBRevision:
         self._files.sort(key=lambda x: x["name"])
         return self._files
 
-    def calc_delta(self, current_rev: Optional[DBRevision]):
+    def calc_delta(self, current_rev: DBRevision | None):
         """Calculate the list of files to download and to delete.
         Param current_rev is the revision that's currently checked out.
         If it's None, the repository is empty.
diff --git a/lib/git_exporter.py b/lib/git_exporter.py
index 533bf4d..76313df 100644
--- a/lib/git_exporter.py
+++ b/lib/git_exporter.py
@@ -40,7 +40,7 @@ class GitExporter:
     def check_repo_state(self, flats, branch_state):
         state_data = dict()
         if os.path.exists(self.state_file):
-            with open(self.state_file, "r") as f:
+            with open(self.state_file) as f:
                 state_data = yaml.safe_load(f)
                 if type(state_data) != dict:
                     state_data = {}
diff --git a/lib/tree_builder.py b/lib/tree_builder.py
index 48bfe5c..65a5594 100644
--- a/lib/tree_builder.py
+++ b/lib/tree_builder.py
@@ -138,7 +138,7 @@ class TreeBuilder:
                 self.requests.add(node.revision.request_id)
 
         class FindMergeWalker(AbstractWalker):
-            def __init__(self, builder: TreeBuilder, requests: Dict) -> None:
+            def __init__(self, builder: TreeBuilder, requests: dict) -> None:
                 super().__init__()
                 self.source_revisions = dict()
                 self.builder = builder