diff --git a/pyproject.toml b/pyproject.toml
index 31b6af9..1e1f9c0 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -15,7 +15,7 @@ dependencies = ["specklepy==3.1.0",
 
 [project.optional-dependencies]
 dev = [
-    "mypy==1.13.0",
+    "mypy==1.20.0",
     "pytest==7.4.4",
     "ruff==0.11.12",
 ]