diff --git a/pyproject.toml b/pyproject.toml
index 80fb61da..ce1f63c0 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [build-system]
-requires = ["flit"]
-build-backend = "flit.buildapi"
+requires = ["flit_core >=2,<4"]
+build-backend = "flit_core.buildapi"
 
 [tool.flit.metadata]
 module = "change_detection"
@@ -17,4 +17,4 @@ requires = [
          "ebmdatalab >=0.0.20"
 ]
 
-description-file = "README.md"
\ No newline at end of file
+description-file = "README.md"