diff --git a/build_rust.py b/build_rust.py
deleted file mode 100644
index 662474dcb4..0000000000
--- a/build_rust.py
+++ /dev/null
@@ -1,23 +0,0 @@
-# A build script for poetry that adds the rust extension.
-
-import os
-from typing import Any, Dict
-
-from setuptools_rust import Binding, RustExtension
-
-
-def build(setup_kwargs: Dict[str, Any]) -> None:
-    original_project_dir = os.path.dirname(os.path.realpath(__file__))
-    cargo_toml_path = os.path.join(original_project_dir, "rust", "Cargo.toml")
-
-    extension = RustExtension(
-        target="synapse.synapse_rust",
-        path=cargo_toml_path,
-        binding=Binding.PyO3,
-        py_limited_api=True,
-        # We force always building in release mode, as we can't tell the
-        # difference between using `poetry` in development vs production.
-        debug=False,
-    )
-    setup_kwargs.setdefault("rust_extensions", []).append(extension)
-    setup_kwargs["zip_safe"] = False
diff --git a/pyproject.toml b/pyproject.toml
index bf51276f4a..5cc77b5b0e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -133,10 +133,6 @@ exclude = [
     { path = "synapse/*.so", format = "sdist"}
 ]
 
-[tool.poetry.build]
-script = "build_rust.py"
-generate-setup-file = true
-
 [tool.poetry.scripts]
 synapse_homeserver = "synapse.app.homeserver:main"
 synapse_worker = "synapse.app.generic_worker:main"
@@ -382,7 +378,16 @@ furo = ">=2022.12.7,<2024.0.0"
 # provided we check that it's safe to do so (i.e. that CI passes).
 requires = ["poetry-core>=1.1.0,<=1.7.0", "setuptools_rust>=1.3,<=1.7.0"]
 build-backend = "poetry.core.masonry.api"
+# Should this now be build-backend = "setuptools.build_meta"?
 
+[[tool.setuptools-rust.ext-modules]]
+target = "synapse.synapse_rust"
+path = "rust/Cargo.toml"
+binding = "PyO3"
+py-limited-api = true
+# We force always building in release mode, as we can't tell the
+# difference between using `poetry` in development vs production.
+debug = false
 
 [tool.cibuildwheel]
 # Skip unsupported platforms (by us or by Rust).