1 files changed, 1 insertions, 1 deletions

diff --git a/tox.ini b/tox.ini
index d4c3022b..45df8722 100644
--- a/tox.ini
+++ b/tox.ini
@@ -10,7 +10,7 @@ deps =
     # This must be kept in sync with Jenkinsfile and .travis/install.sh
     coverage
     ./vectors
-passenv = ARCHFLAGS LDFLAGS CFLAGS INCLUDE LIB LD_LIBRARY_PATH USERNAME
+passenv = ARCHFLAGS LDFLAGS CFLAGS INCLUDE LIB LD_LIBRARY_PATH USERNAME PYTHONIOENCODING
 commands =
     pip list
     # We use parallel mode and then combine here so that coverage.py will take