diff --git a/pyproject.toml b/pyproject.toml
index 06278b6..4d5b97c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -44,7 +44,7 @@ default-groups = ["dev"]
 exclude-newer = "1 week"
 
 [build-system]
-requires = ["flit_core<4"]
+requires = ["flit_core<5"]
 build-backend = "flit_core.buildapi"
 
 [tool.flit.sdist]