diff --git a/rosdistro_reviewer/git_lines.py b/rosdistro_reviewer/git_lines.py
index e5b9047..431d095 100644
--- a/rosdistro_reviewer/git_lines.py
+++ b/rosdistro_reviewer/git_lines.py
@@ -46,48 +46,48 @@ def get_added_lines(
     :returns: Mapping of relative file paths to sequences of line number
         ranges, or None if no changes were detected
     """
-    repo = Repo(path)
-
-    if head_ref is not None:
-        head = repo.commit(head_ref)
-    else:
-        head = None
-
-    if target_ref is not None:
-        target = repo.commit(target_ref)
-    elif head is not None:
-        target = head.parents[0]
-    else:
-        target = repo.head.commit
-
-    if head is not None:
-        for base in repo.merge_base(target, head):
-            if base is not None:
-                break
+    with Repo(path) as repo:
+        if head_ref is not None:
+            head = repo.commit(head_ref)
         else:
-            raise RuntimeError(
-                f"No merge base found between '{target_ref}' and '{head_ref}'")
-    else:
-        base = target
-
-    diffs = base.diff(head, paths, True)
-
-    lines: Dict[str, List[int]] = {}
-    for diff in diffs:
-        if not diff.b_path:
-            continue
-        patch = f"""--- {diff.a_path if diff.a_path else '/dev/null'}
+            head = None
+
+        if target_ref is not None:
+            target = repo.commit(target_ref)
+        elif head is not None:
+            target = head.parents[0]
+        else:
+            target = repo.head.commit
+
+        if head is not None:
+            for base in repo.merge_base(target, head):
+                if base is not None:
+                    break
+            else:
+                raise RuntimeError(
+                    f"No merge base found between '{target_ref}' and "
+                    f"'{head_ref}'")
+        else:
+            base = target
+
+        diffs = base.diff(head, paths, True)
+
+        lines: Dict[str, List[int]] = {}
+        for diff in diffs:
+            if not diff.b_path:
+                continue
+            patch = f"""--- {diff.a_path if diff.a_path else '/dev/null'}
 +++ {diff.b_path}
 {diff.diff.decode()}"""
-        patchset = unidiff.PatchSet(patch)
-        for file in patchset:
-            for hunk in file:
-                for line in hunk:
-                    if line.line_type != unidiff.LINE_TYPE_ADDED:
-                        continue
-                    lines.setdefault(
-                        os.path.normpath(file.path),
-                        []).append(line.target_line_no)
+            patchset = unidiff.PatchSet(patch)
+            for file in patchset:
+                for hunk in file:
+                    for line in hunk:
+                        if line.line_type != unidiff.LINE_TYPE_ADDED:
+                            continue
+                        lines.setdefault(
+                            os.path.normpath(file.path),
+                            []).append(line.target_line_no)
 
     if not lines:
         return None
diff --git a/rosdistro_reviewer/yaml_changes.py b/rosdistro_reviewer/yaml_changes.py
index a8af9b3..8805940 100644
--- a/rosdistro_reviewer/yaml_changes.py
+++ b/rosdistro_reviewer/yaml_changes.py
@@ -79,14 +79,13 @@ def get_changed_yaml(
     if not changes:
         return None
 
-    repo = Repo(path)
-
     data = {}
     if head_ref is not None:
-        for yaml_path in paths:
-            data[yaml_path] = yaml.load(
-                repo.tree(head_ref)[yaml_path].data_stream,
-                Loader=AnnotatedSafeLoader)
+        with Repo(path) as repo:
+            for yaml_path in paths:
+                data[yaml_path] = yaml.load(
+                    repo.tree(head_ref)[yaml_path].data_stream,
+                    Loader=AnnotatedSafeLoader)
     else:
         for yaml_path in paths:
             with (path / yaml_path).open('r') as f: