diff --git a/pyproject.toml b/pyproject.toml
index a55ae978..b6091652 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,5 +1,5 @@
 [build-system]
-requires = ["flit_core >=3.4,<4"]
+requires = ["flit_core >=3.4,<5"]
 build-backend = "flit_core.buildapi"
 
 [project]
@@ -58,15 +58,15 @@ testing-no-myst = [
 ]
 
 theme-furo = ["furo~=2025.12"]
-theme-pydata = ["pydata-sphinx-theme~=0.20.0"]
+theme-pydata = ["pydata-sphinx-theme>=0.20,<0.22"]
 theme-rtd = ["sphinx-rtd-theme~=3.1"]
 theme-sbt = ["sphinx-book-theme~=1.2"]
 theme-im = ["sphinx-immaterial~=0.13.9"]
 
 [dependency-groups]
 # keep in sync with the mirrors-mypy / ruff-pre-commit revs in .pre-commit-config.yaml
-mypy = ["mypy==2.3.0"]
-ruff = ["ruff==0.15.21"]
+mypy = ["mypy==2.3.1"]
+ruff = ["ruff==0.16.5"]
 
 [tool.flit.sdist]
 exclude = [