diff --git a/Dockerfile b/Dockerfile
index ac3df0d..4debc36 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -4,7 +4,8 @@ FROM debian:9
 
 # install build tools and dependencies
 
-RUN apt-get update && apt-get install -y \
+RUN apt-get update && \
+    apt-get install -y \
     build-essential curl unzip git python3 python3-pip gcc-arm-none-eabi libnewlib-arm-none-eabi
 
 ENV PROTOBUF_VERSION=3.4.0
diff --git a/Dockerfile.emulator b/Dockerfile.emulator
index f8c3dad..7f0a249 100644
--- a/Dockerfile.emulator
+++ b/Dockerfile.emulator
@@ -7,7 +7,8 @@ FROM debian:9
 RUN dpkg --add-architecture i386 && \
     apt-get update && \
     apt-get install -y \
-    build-essential curl unzip git python3 python3-pip gcc-arm-none-eabi libnewlib-arm-none-eabi libsdl2-dev:i386 libsdl2-image-dev:i386 gcc-multilib
+    build-essential curl unzip git python3 python3-pip gcc-arm-none-eabi libnewlib-arm-none-eabi \
+    libsdl2-dev:i386 libsdl2-image-dev:i386 gcc-multilib
 
 ENV PROTOBUF_VERSION=3.4.0
 RUN curl -LO "https://github.com/google/protobuf/releases/download/v${PROTOBUF_VERSION}/protoc-${PROTOBUF_VERSION}-linux-x86_64.zip"