diff --git a/ubuntu-dev/ubuntu-dev.dockerfile b/ubuntu-dev/ubuntu-dev.dockerfile
index 3329fd2..d931b47 100644
--- a/ubuntu-dev/ubuntu-dev.dockerfile
+++ b/ubuntu-dev/ubuntu-dev.dockerfile
@@ -1,29 +1,26 @@
-FROM ubuntu:16.04
+FROM ubuntu:18.04
 
 # Install HTTPS transport for Ubuntu package sources.
 RUN apt-get update \
- && apt-get install -y --no-install-recommends apt-transport-https ca-certificates software-properties-common \
+ && apt-get install -y --no-install-recommends apt-transport-https ca-certificates software-properties-common gpg-agent \
  && rm -rf /var/lib/apt/lists/*
 
 # Add source for the latest Clang packages.
 COPY llvm-snapshot.gpg.key /tmp
-RUN echo "deb https://apt.llvm.org/xenial/ llvm-toolchain-xenial-6.0 main" > /etc/apt/sources.list.d/llvm.list \
+RUN echo "deb https://apt.llvm.org/bionic/ llvm-toolchain-bionic-6.0 main" > /etc/apt/sources.list.d/llvm.list \
  && apt-key add /tmp/llvm-snapshot.gpg.key \
  && rm -f /tmp/llvm-snapshot.gpg.key
 
 # Add source for the latest Git packages.
 RUN add-apt-repository ppa:git-core/ppa
 
-# Add source for the latest Mercurial packages.
-RUN add-apt-repository ppa:mercurial-ppa/releases
-
 # Add source for the latest Neovim packages.
 RUN add-apt-repository ppa:neovim-ppa/stable
 
 # Install basic development packages.
 RUN __LLVM_VERSION__="6.0" \
  && apt-get update \
- && apt-get install -y --no-install-recommends \
+ && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
   autoconf \
   automake \
   bash-completion \