diff --git a/requirements-dev.txt b/requirements-dev.txt
index e727f36..b3e9a10 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -3,5 +3,7 @@
 
 pytest>=7.4
 ruff>=0.6
-build>=1.2
+# build 1.5 requires Python >=3.10; use the compatible series on Python 3.9.
+build>=1.2,<1.5; python_version < "3.10"
+build>=1.6.1; python_version >= "3.10"
 pyinstaller>=6.6