diff --git a/requirements_tests.txt b/requirements_tests.txt
index 2342e6b..9d17770 100644
--- a/requirements_tests.txt
+++ b/requirements_tests.txt
@@ -1,2 +1,3 @@
 lxml==5.2.2
 pytest==8.2.2
+typing-extensions==4.12.2
diff --git a/setup.py b/setup.py
index 03b7dfb..2446b3a 100644
--- a/setup.py
+++ b/setup.py
@@ -28,6 +28,7 @@
     ],
     test_suite="tests",
     tests_require=["lxml"],
+    install_requires=["typing_extensions>=4.1"],
     platforms="any",
     classifiers=[
         "Environment :: Web Environment",