diff --git a/tox.ini b/tox.ini
index b9a102a64..0ed9e4c11 100644
--- a/tox.ini
+++ b/tox.ini
@@ -17,6 +17,7 @@ skip_missing_interpreters = true
 [testenv]
 description = run the unit tests under {basepython}
 commands = python setup.py test -a "{posargs:-n auto}"
+passenv = LDFLAGS CFLAGS
 
 [testenv:fmt]
 description = run code formatting using black