diff --git a/Cargo.toml b/Cargo.toml
index 8a183a4..3f5954c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,6 +15,7 @@ serde = "1.0"
 serde_json = "1.0"
 cpython = { version = "0.1", default-features = false }
 cpython-json = { version = "0.2", default-features = false }
+python3-sys = { version = "0.1.3", features = ["python-3-4"], optional = true }
 
 [features]
 default = ["cpython/python3-sys"]
diff --git a/builder/Dockerfile b/builder/Dockerfile
index 39125ae..7809331 100644
--- a/builder/Dockerfile
+++ b/builder/Dockerfile
@@ -1,7 +1,5 @@
-FROM amazonlinux:latest
+FROM lambci/lambda:build-python3.6
 RUN curl https://sh.rustup.rs -sSf | sh -s -- -y --default-toolchain stable
-RUN yum install -y bzip2-devel gcc gcc-c++ git openssl-devel python27-devel python36-devel readline-devel sqlite-devel zip \
- && yum clean all
 ADD build.sh /usr/local/bin/
 VOLUME ["/code"]
 WORKDIR /code
diff --git a/builder/README.md b/builder/README.md
index befbbda..bf2036c 100644
--- a/builder/README.md
+++ b/builder/README.md
@@ -5,11 +5,11 @@ The `Dockerfile` and `build.sh` script here help you build Lambda functions agai
 It's automatically built on Docker Hub as [ilianaw/crowbar-builder](https://hub.docker.com/r/ilianaw/crowbar-builder/) and can be invoked like this from your source tree:
 
 ```bash
-docker run --rm -v $(pwd):/code:ro ilianaw/crowbar-builder > lambda.zip
+docker run --rm -v $(pwd):/code:ro -e CARGO_FLAGS="--features crowbar/python3-sys" ilianaw/crowbar-builder > lambda.zip
 ```
 
 If you need extra packages, add them as arguments:
 
 ```bash
-docker run --rm -v $(pwd):/code:ro ilianaw/crowbar-builder openssl-devel > lambda.zip
+docker run --rm -v $(pwd):/code:ro -e CARGO_FLAGS="--features crowbar/python3-sys" ilianaw/crowbar-builder openssl-devel > lambda.zip
 ```