diff --git a/pyproject.toml b/pyproject.toml
index 36bbf98..87fa7c2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -9,4 +9,5 @@ requires = [
     "setuptools",
     "wheel",
     "Cython"
-]
\ No newline at end of file
+]
+build-backend = "setuptools.build_meta"
diff --git a/pysaliency/external_datasets/dut_omrom.py b/pysaliency/external_datasets/dut_omrom.py
index 78b9c08..e363488 100644
--- a/pysaliency/external_datasets/dut_omrom.py
+++ b/pysaliency/external_datasets/dut_omrom.py
@@ -3,6 +3,7 @@
 import glob
 import os
 import zipfile
+from typing import Tuple
 
 import numpy as np
 from scipy.io import loadmat
@@ -17,7 +18,7 @@
 from .utils import _load, create_stimuli
 
 
-def get_DUT_OMRON(location=None) -> tuple[Stimuli, ScanpathFixations]:
+def get_DUT_OMRON(location=None) -> Tuple[Stimuli, ScanpathFixations]:
     """
     Loads or downloads the DUT-OMRON fixation dataset.
     The dataset consists of 5168 natural images with