diff --git a/Dockerfile b/Dockerfile
index 00f7a76..be8ef3f 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM python:3
+FROM python:3.5
 
 WORKDIR /usr/src/app
 
@@ -7,4 +7,4 @@ RUN pip install --no-cache-dir -r requirements.txt
 
 COPY . .
 
-CMD [ "python", "./run.py" ]
\ No newline at end of file
+CMD [ "python", "./run.py" ]
diff --git a/requirements.txt b/requirements.txt
index 4b07d47..888a3bd 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,8 @@
 slackbot==0.5.1
 pytz==2018.4
 tzlocal==1.5.1
-tbapy==1.3.0
\ No newline at end of file
+tbapy==1.3.0
+
+# https://github.com/slackapi/python-slackclient/issues/127#issuecomment-468224122
+# https://github.com/slackapi/python-slackclient/pull/387
+websocket-client==0.54.0