diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000000000000000000000000000000000000..4f9cefda0776745d43e853a665614dfb02c4c45e
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+*.iml
+/.idea/*
+!/.idea/copyright/
+.DS_Store
diff --git a/Dockerfile b/Dockerfile
index 4ce3d07e5c3f9b8c5133cb660323e9215e72dc88..6697a16d5fdaf9f793a7fc8c6b481c6bda877faf 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,7 +1,7 @@
 FROM openjdk:8-jdk as builder
 
 # define arguments for versions to be used for platform and build tools
-ARG PLATFORM=32
+ARG PLATFORM=31
 ARG BUILD_TOOLS=32.0.0
 
 RUN apt-get --quiet update --yes && \