diff --git a/docker/Dockerfile b/docker/Dockerfile
index 9150ad1..247ad44 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -1,13 +1,13 @@
-FROM rust:1.56.1-slim
+FROM rustlang/rust:nightly-slim
 
-ARG MDBOOK_VERSION="0.4.13"
+ARG MDBOOK_VERSION="0.4.43"
 ARG MDBOOK_TRANSCHECK_VERSION="0.2.8"
 
 # Install mdBook
-RUN cargo install mdbook --vers ${MDBOOK_VERSION}
+RUN cargo install mdbook --locked --vers ${MDBOOK_VERSION}
 
 # Install mdbook-transcheck
-RUN cargo install mdbook-transcheck --vers ${MDBOOK_TRANSCHECK_VERSION}
+RUN cargo install mdbook-transcheck --locked --vers ${MDBOOK_TRANSCHECK_VERSION}
 
 # Install CircleCI Requirements
 # https://circleci.com/docs/2.0/custom-images/#required-tools-for-primary-containers