diff --git a/packages/http/httpx/pyproject.toml b/packages/http/httpx/pyproject.toml
index 2db60379..ffddc996 100644
--- a/packages/http/httpx/pyproject.toml
+++ b/packages/http/httpx/pyproject.toml
@@ -1,5 +1,5 @@
 [build-system]
-requires = ["flit_core>=3.2,<4"]
+requires = ["flit_core>=3.2,<5"]
 build-backend = "flit_core.buildapi"
 
 [project]