diff --git a/tox.ini b/tox.ini
index dfd4306..f2407a5 100644
--- a/tox.ini
+++ b/tox.ini
@@ -18,6 +18,7 @@ commands = python -m pip install --upgrade pip
 deps =
     -r requirements.txt
     .[tests]
+setenv = PYTHONPATH = {toxinidir}/src
 commands = python -m pytest --basetemp={envtmpdir} {posargs}
     tox
 [testenv:integrationtests]
@@ -25,6 +26,7 @@ commands = python -m pytest --basetemp={envtmpdir} {posargs}
 deps =
     -r requirements.txt
     {[testenv:unittests]deps}
+setenv = PYTHONPATH = {toxinidir}/src
 commands = python -m pytest --basetemp={envtmpdir} {posargs}