diff --git a/pyproject.toml b/pyproject.toml
index 98ab112ab459a..0c3e078d8761a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@
 requires = [
     "setuptools>=51.0.0",
     "wheel",
-    "Cython>=0.29.24,<3",  # Note: sync with setup.py
+    "Cython>=0.29.24,<3",  # Note: sync with setup.py, environment.yml and asv.conf.json
     "oldest-supported-numpy>=0.10"
 ]
 # uncomment to enable pep517 after versioneer problem is fixed.
diff --git a/setup.py b/setup.py
index f5151621c9efe..ca71510c5f051 100755
--- a/setup.py
+++ b/setup.py
@@ -37,7 +37,8 @@ def is_platform_mac():
     return sys.platform == "darwin"
 
 
-min_cython_ver = "0.29.24"  # note: sync with pyproject.toml
+# note: sync with pyproject.toml, environment.yml and asv.conf.json
+min_cython_ver = "0.29.24"
 
 try:
     from Cython import (