diff --git a/backend/Dockerfile.multi b/backend/Dockerfile.multi
index e1dca7d..ce85bd9 100644
--- a/backend/Dockerfile.multi
+++ b/backend/Dockerfile.multi
@@ -2,7 +2,7 @@
 # Python dependencies builder
 #
 # Full official Debian-based Python image
-FROM python:3-stretch AS builder
+FROM python:3.6-stretch AS builder
 
 # Always set a working directory
 WORKDIR /app
@@ -34,7 +34,7 @@ RUN pip install --no-cache-dir -r requirements.txt
 # Actual container
 #
 #
-FROM python:3-slim-stretch AS app
+FROM python:3.6-slim-stretch AS app
 
 # Extra python env
 ENV PATH="/venv/bin:$PATH"