diff --git a/pyproject.toml b/pyproject.toml
index af15fd3..61b7e9e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -8,7 +8,7 @@ package = true
 [dependency-groups]
 dev = [
     "check-manifest",
-    "flit>=3.12,<4",
+    "flit>=3.12,<5",
     "mypy==2.1.0",  # https://github.com/python/mypy
     "pre-commit>=4,<5",  # https://github.com/pre-commit/pre-commit
     "ruff>=0.12,<1.0",