diff --git a/docker/backend-dev-e2e/Dockerfile b/docker/backend-dev-e2e/Dockerfile
index 3866d011..d5e174d6 100644
--- a/docker/backend-dev-e2e/Dockerfile
+++ b/docker/backend-dev-e2e/Dockerfile
@@ -46,7 +46,7 @@ USER libervia
 
 RUN \
     # pytest and its plugins
-    pip install pytest pytest-timeout pytest-dependency \
+    pip install pytest pytest-timeout pytest-dependency pytest-twisted \
     # needed to test libervia-cli
     sh \
     # needed to test libervia