diff --git a/build-install-dumb-init.sh b/build-install-dumb-init.sh
index 261f5f9..f9daf09 100644
--- a/build-install-dumb-init.sh
+++ b/build-install-dumb-init.sh
@@ -58,7 +58,7 @@ pip3 install virtualenv || exit 1
 
 virtualenv $builddir/venv || exit 1
 . $builddir/venv/bin/activate || exit 1
-pip3 install setuptools tox || exit 1
+pip3 install setuptools tox py || exit 1
 )
 
 . $builddir/venv/bin/activate || exit 1