diff --git a/pyproject.toml b/pyproject.toml
index fc860a8fdf4..32bb27525a0 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -15,7 +15,7 @@ dependencies = [
     # When changing a floor, verify it installs + imports on every supported
     # Python with: `uv pip install --resolution=lowest-direct .`
     "fastuuid>=0.14.0,<1.0; python_version < '3.15'",
-    "filelock>=3.16.1,<4.0",
+    "filelock>=3.16.1,<5",
     "httpx[http2]>=0.28.0,<1.0",
     "openai>=2.20.0,<4.0.0",
     "python-dotenv>=1.0.0,<2.0",