diff --git a/setup.py b/setup.py
index 5b92ffc2..0051819a 100644
--- a/setup.py
+++ b/setup.py
@@ -80,7 +80,7 @@
             "mypy==v0.910 ; python_version<'3.6'",
             "mypy==v0.971 ; python_version>='3.6' and python_version<'3.7'",
             "mypy==v1.4.1 ; python_version>='3.7' and python_version<'3.8'",
-            "mypy==v1.8.0 ; python_version>='3.8'",
+            "mypy==v1.9.0 ; python_version>='3.8'",
             # Docs.
             "Sphinx==7.2.5 ; python_version>='3.9'",
             "sphinx-autobuild==2024.2.4 ; python_version>='3.9'",