diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 00000000..a9eb8aa9
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,8 @@
+[build-system]
+requires = [
+    # Also declared in requirements.txt, if updating here please also update
+    # there
+    "Cython~=0.29.13",
+    "setuptools >= 35.0.2",
+]
+build-backend = "setuptools.build_meta"
diff --git a/requirements.txt b/requirements.txt
index a2cce258..180fe851 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1 +1,2 @@
+# Also declared in pyproject.toml, if updating here please also update there
 Cython~=0.29.13
diff --git a/tox.ini b/tox.ini
index 607b182e..ace1ba90 100644
--- a/tox.ini
+++ b/tox.ini
@@ -5,6 +5,7 @@ envlist =
     {pypy,pypy3}-pure,
     py27-x86,
     py34-x86,
+isolated_build = true
 
 [variants:pure]
 setenv=