diff --git a/backend/Dockerfile b/backend/Dockerfile
index a091b8a..a5200c4 100644
--- a/backend/Dockerfile
+++ b/backend/Dockerfile
@@ -1,5 +1,5 @@
 # Use an official Python runtime as a parent image
-FROM python:3.7
+FROM python:3.5
 
 # Clone third-party repos.
 RUN git clone --depth 1 https://github.com/UKPLab/emnlp2017-bilstm-cnn-crf.git /emnlp2017-bilstm-cnn-crf
diff --git a/backend/requirements.txt b/backend/requirements.txt
index a4912b8..e1820d7 100644
--- a/backend/requirements.txt
+++ b/backend/requirements.txt
@@ -1,6 +1,6 @@
-flask~=2.0
+flask~=1.0
 flasgger~=0.9.4
 flask_restful~=0.3.7
-torch~=0.4.1
+torch~=1.0
 torchvision~=0.2.1
-pyyaml~=6.0
+pyyaml~=5.3