diff --git a/antarest/matrixstore/repository.py b/antarest/matrixstore/repository.py
index ee6fefabea..03d8f65b93 100644
--- a/antarest/matrixstore/repository.py
+++ b/antarest/matrixstore/repository.py
@@ -229,9 +229,7 @@ def save(self, content: t.Union[t.List[t.List[MatrixData]], npt.NDArray[np.float
             # Avoid having to save the matrix again (that's the whole point of using a hash).
             return matrix_hash
 
-        lock_file = matrix_path.parent.joinpath(
-            f"{matrix_hash}.tsv.lock"
-        )  # use tsv lock to stay consistent with old data
+        lock_file = matrix_path.with_suffix(".tsv.lock")  # use tsv lock to stay consistent with old data
         for internal_format in InternalMatrixFormat:
             matrix_in_another_format_path = self.bucket_dir.joinpath(f"{matrix_hash}.{internal_format}")
             if matrix_in_another_format_path.exists():
@@ -282,5 +280,5 @@ def delete(self, matrix_hash: str) -> None:
 
         # IMPORTANT: Deleting the lock file under Linux can make locking unreliable.
         # Abandoned lock files are deleted here to maintain consistent behavior.
-        lock_file = matrix_path.parent.joinpath(f"{matrix_hash}.tsv.lock")
+        lock_file = matrix_path.with_suffix(".tsv.lock")
         lock_file.unlink(missing_ok=True)
diff --git a/tests/matrixstore/test_repository.py b/tests/matrixstore/test_repository.py
index d63f63cbec..621f624e9b 100644
--- a/tests/matrixstore/test_repository.py
+++ b/tests/matrixstore/test_repository.py
@@ -304,7 +304,7 @@ def test_mixed_formats(self, tmp_path: str, matrix_format: str) -> None:
                     associated_hash = "d73f023a3f852bf2e5c6d836cd36cd930d0091dcba7f778161c707e1c58222b0"
                     matrix_path = matrix_content_repo.bucket_dir.joinpath(f"{associated_hash}.{saved_format}")
                     saved_format.save_matrix(df, matrix_path)
-                    lock_path = matrix_content_repo.bucket_dir.joinpath(f"{associated_hash}.tsv.lock")
+                    lock_path = matrix_path.with_suffix(".tsv.lock")
                     lock_path.touch()
 
                     # asserts the saved matrix object exists
@@ -331,5 +331,5 @@ def test_mixed_formats(self, tmp_path: str, matrix_format: str) -> None:
                     assert not saved_matrix_files
                     repo_matrix_files = list(matrix_content_repo.bucket_dir.glob(f"*.{repository_format}"))
                     assert len(repo_matrix_files) == 1
-                    new_matrix_path = matrix_content_repo.bucket_dir.joinpath(f"{associated_hash}.{repository_format}")
+                    new_matrix_path = matrix_content_repo.bucket_dir.with_suffix(f".{repository_format}")
                     assert repo_matrix_files[0] == new_matrix_path