diff --git a/pyproject.toml b/pyproject.toml
index ed826f81..6dde0165 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 # Build system requirements.
 [build-system]
-requires = ["flit_core >=3.11,<4"]
+requires = ["flit_core >=3.11,<5"]
 build-backend = "flit_core.buildapi"
 
 # Project metadata