diff --git a/src/pkgs/sage_conf-relocatable/tox.ini b/src/pkgs/sage_conf-relocatable/tox.ini
index b59cd9ee7ec..c06184437a3 100644
--- a/src/pkgs/sage_conf-relocatable/tox.ini
+++ b/src/pkgs/sage_conf-relocatable/tox.ini
@@ -5,6 +5,11 @@ envlist = python
 passenv =
    MAKE
 
+basepython =
+   macos-python3_xcode:       /usr/bin/python3
+   macos-python3.8:           /Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.8/bin/python3
+   macos-python3.7:           /Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.7/bin/python3
+
 setenv =
    HOME={envdir}
    # /usr/local/opt/xz/bin is a workaround for homebrew so that /usr/bin/python3