diff --git a/Dockerfile b/Dockerfile
index 2ad3489..466e0bc 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM ubuntu:latest
+FROM ubuntu:18.04
 
 # Install Python and Boost.
 RUN \
@@ -16,4 +16,4 @@ ENV LC_ALL=C.UTF-8
 ENV LANG=C.UTF-8
 
 # Define default command.
-CMD ["bash"]
\ No newline at end of file
+CMD ["bash"]