diff --git a/src/docker/ubuntu12.04/Dockerfile b/src/docker/ubuntu12.04/Dockerfile
deleted file mode 100644
index 92ec74e..0000000
--- a/src/docker/ubuntu12.04/Dockerfile
+++ /dev/null
@@ -1,82 +0,0 @@
-# Copyright 2010-2015, Google Inc.
-# All rights reserved.
-#
-# Redistribution and use in source and binary forms, with or without
-# modification, are permitted provided that the following conditions are
-# met:
-#
-#     * Redistributions of source code must retain the above copyright
-# notice, this list of conditions and the following disclaimer.
-#     * Redistributions in binary form must reproduce the above
-# copyright notice, this list of conditions and the following disclaimer
-# in the documentation and/or other materials provided with the
-# distribution.
-#     * Neither the name of Google Inc. nor the names of its
-# contributors may be used to endorse or promote products derived from
-# this software without specific prior written permission.
-#
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-FROM ubuntu:12.04.5
-
-ENV DEBIAN_FRONTEND noninteractive
-
-# Package installation
-RUN apt-get update
-## Common packages for linux build environment
-RUN apt-get install -y g++ python pkg-config subversion git curl bzip2 unzip make
-## Packages for linux desktop version
-RUN apt-get install -y libibus-1.0-dev libdbus-1-dev libglib2.0-dev subversion libqt4-dev libzinnia-dev tegaki-zinnia-japanese libgtk2.0-dev libxcb-xfixes0-dev
-## Packages for Android
-RUN apt-get install -y --no-install-recommends openjdk-7-jdk openjdk-7-jre-headless ant ia32-libs ia32-libs-multiarch zip
-## Packages for NaCl
-RUN apt-get install -y libc6:i386 libstdc++6:i386 libstdc++6-4.4-dev
-## For emacsian
-RUN apt-get install -y emacs
-
-ENV HOME /home/mozc_builder
-RUN useradd --create-home --shell /bin/bash --base-dir /home mozc_builder
-USER mozc_builder
-
-# SDK setup
-RUN mkdir -p /home/mozc_builder/work
-WORKDIR /home/mozc_builder/work
-
-## Android SDK/NDK
-RUN curl -L http://dl.google.com/android/ndk/android-ndk-r10d-linux-x86_64.bin -O && chmod u+x android-ndk-r10d-linux-x86_64.bin && ./android-ndk-r10d-linux-x86_64.bin && rm android-ndk-r10d-linux-x86_64.bin
-RUN curl -L http://dl.google.com/android/android-sdk_r24.0.2-linux.tgz | tar -zx
-ENV ANDROID_NDK_HOME /home/mozc_builder/work/android-ndk-r10d
-ENV ANDROID_HOME /home/mozc_builder/work/android-sdk-linux
-ENV PATH $PATH:${ANDROID_HOME}/tools:${ANDROID_HOME}/platform-tools:${ANDROID_NDK_HOME}
-RUN echo y | android update sdk --all --force --no-ui --filter android-21
-RUN echo y | android update sdk --all --force --no-ui --filter build-tools-21.0.2
-RUN echo y | android update sdk --all --force --no-ui --filter extra-android-support
-RUN echo y | android update sdk --all --force --no-ui --filter platform-tool
-
-## NaCl SDK
-RUN curl -LO http://storage.googleapis.com/nativeclient-mirror/nacl/nacl_sdk/nacl_sdk.zip && unzip nacl_sdk.zip && rm nacl_sdk.zip
-RUN cd nacl_sdk && ./naclsdk install pepper_27
-ENV NACL_SDK_ROOT /home/mozc_builder/work/nacl_sdk/pepper_27
-
-## depot_tools
-RUN git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git
-ENV PATH $PATH:/home/mozc_builder/work/depot_tools
-
-# check out Mozc source
-RUN mkdir -p /home/mozc_builder/work/mozc
-WORKDIR /home/mozc_builder/work/mozc
-RUN gclient config http://mozc.googlecode.com/svn/trunk/src
-RUN gclient sync
-
-WORKDIR /home/mozc_builder/work/mozc/src
-ENTRYPOINT bash
diff --git a/src/docker/ubuntu12.04/clobber-make-buildenv.sh b/src/docker/ubuntu12.04/clobber-make-buildenv.sh
deleted file mode 100755
index da51449..0000000
--- a/src/docker/ubuntu12.04/clobber-make-buildenv.sh
+++ /dev/null
@@ -1,31 +0,0 @@
-#!/bin/bash
-# Copyright 2010-2015, Google Inc.
-# All rights reserved.
-#
-# Redistribution and use in source and binary forms, with or without
-# modification, are permitted provided that the following conditions are
-# met:
-#
-#     * Redistributions of source code must retain the above copyright
-# notice, this list of conditions and the following disclaimer.
-#     * Redistributions in binary form must reproduce the above
-# copyright notice, this list of conditions and the following disclaimer
-# in the documentation and/or other materials provided with the
-# distribution.
-#     * Neither the name of Google Inc. nor the names of its
-# contributors may be used to endorse or promote products derived from
-# this software without specific prior written permission.
-#
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-docker build --no-cache --rm -t $USER/mozc_ubuntu12.04 .
diff --git a/src/docker/ubuntu12.04/enter-buildenv.sh b/src/docker/ubuntu12.04/enter-buildenv.sh
deleted file mode 100755
index a41803a..0000000
--- a/src/docker/ubuntu12.04/enter-buildenv.sh
+++ /dev/null
@@ -1,31 +0,0 @@
-#!/bin/bash
-# Copyright 2010-2015, Google Inc.
-# All rights reserved.
-#
-# Redistribution and use in source and binary forms, with or without
-# modification, are permitted provided that the following conditions are
-# met:
-#
-#     * Redistributions of source code must retain the above copyright
-# notice, this list of conditions and the following disclaimer.
-#     * Redistributions in binary form must reproduce the above
-# copyright notice, this list of conditions and the following disclaimer
-# in the documentation and/or other materials provided with the
-# distribution.
-#     * Neither the name of Google Inc. nor the names of its
-# contributors may be used to endorse or promote products derived from
-# this software without specific prior written permission.
-#
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-docker run --interactive --tty --rm $USER/mozc_ubuntu12.04
diff --git a/src/docker/ubuntu12.04/make-buildenv.sh b/src/docker/ubuntu12.04/make-buildenv.sh
deleted file mode 100755
index 12f021e..0000000
--- a/src/docker/ubuntu12.04/make-buildenv.sh
+++ /dev/null
@@ -1,31 +0,0 @@
-#!/bin/bash
-# Copyright 2010-2015, Google Inc.
-# All rights reserved.
-#
-# Redistribution and use in source and binary forms, with or without
-# modification, are permitted provided that the following conditions are
-# met:
-#
-#     * Redistributions of source code must retain the above copyright
-# notice, this list of conditions and the following disclaimer.
-#     * Redistributions in binary form must reproduce the above
-# copyright notice, this list of conditions and the following disclaimer
-# in the documentation and/or other materials provided with the
-# distribution.
-#     * Neither the name of Google Inc. nor the names of its
-# contributors may be used to endorse or promote products derived from
-# this software without specific prior written permission.
-#
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-docker build --rm -t $USER/mozc_ubuntu12.04 .
diff --git a/src/mozc_version_template.txt b/src/mozc_version_template.txt
index 908edee..131d7b6 100644
--- a/src/mozc_version_template.txt
+++ b/src/mozc_version_template.txt
@@ -1,6 +1,6 @@
 MAJOR=2
 MINOR=16
-BUILD=2019
+BUILD=2020
 REVISION=102
 # NACL_DICTIONARY_VERSION is the target version of the system dictionary to be
 # downloaded by NaCl Mozc.