diff --git a/tox.ini b/tox.ini
index 2a1c134..044e638 100644
--- a/tox.ini
+++ b/tox.ini
@@ -24,6 +24,7 @@ deps = jaconv
        python-barcode
 commands = pytest --cov escpos --cov-report=xml
 passenv = ESCPOS_CAPABILITIES_PICKLE_DIR, ESCPOS_CAPABILITIES_FILE, CI, TRAVIS, TRAVIS_*, APPVEYOR, APPVEYOR_*, CODECOV_*
+setenv = PY_IGNORE_IMPORTMISMATCH=1
 
 [testenv:docs]
 basepython = python