diff --git a/concordia-preprocessor/Dockerfile b/concordia-preprocessor/Dockerfile
index cce5a5a..87674ae 100644
--- a/concordia-preprocessor/Dockerfile
+++ b/concordia-preprocessor/Dockerfile
@@ -10,7 +10,7 @@ ENV LC_ALL pl_PL.UTF-8
 
 RUN add-apt-repository 'deb http://sgjp.pl/apt/ubuntu-xenial xenial main' && apt-get update
 RUN apt-get install --allow-unauthenticated -y git python3 python3-pip morfeusz2
-RUN pip3 install requests
+RUN pip3 install flask flask_restful gunicorn requests
 
 COPY python3-morfeusz2_0.4.0-1_amd64.deb /
 RUN dpkg -i python3-morfeusz2_0.4.0-1_amd64.deb