diff --git a/build/Dockerfile b/build/Dockerfile
index c9987f3e..db84908c 100644
--- a/build/Dockerfile
+++ b/build/Dockerfile
@@ -23,6 +23,7 @@ RUN apt-get update && apt-get install -y --force-yes --no-install-recommends \
 WORKDIR /opt/sipa
 
 COPY --chown=sipa:sipa ./build /opt/sipa/build/
+COPY --chown=sipa:sipa ./wtforms-widgets /opt/sipa/wtforms-widgets
 ARG additional_requirements
 RUN ./build/install_requirements.py $additional_requirements