diff --git a/pyproject.toml b/pyproject.toml
index f9a0893..47d44e2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -32,7 +32,7 @@ Changelog = "https://github.com/allenai/flexolmo/blob/main/CHANGELOG.md"
 [project.optional-dependencies]
 dev = [
     "ruff",
-    "mypy>=1.0,<1.16",
+    "mypy>=1.0,<1.18",
     "black>=23.1,<26.0",
     "isort>=5.12,<6.1",
     "pytest",