diff --git a/build/docker/README.md b/build/docker/README.md
index 56b98a9..b65f74b 100644
--- a/build/docker/README.md
+++ b/build/docker/README.md
@@ -168,7 +168,7 @@
 | Language  | ubuntu-xenial | ubuntu-bionic | Notes |
 | :-------- | :------------ | :------------ | :---- |
 | as of     | Mar 06, 2018  | Jan 21, 2019  |       |
-| as3       |               |               | Not in CI |
+| as3       |               | 4.6.0         |       |
 | C++ gcc   | 5.4.0         | 7.3.0         |       |
 | C++ clang | 3.8           | 6.0           |       |
 | C# (mono) | 4.2.1.0       | 4.6.2.7       |       |
diff --git a/build/docker/ubuntu-bionic/Dockerfile b/build/docker/ubuntu-bionic/Dockerfile
index db19112..a75af31 100644
--- a/build/docker/ubuntu-bionic/Dockerfile
+++ b/build/docker/ubuntu-bionic/Dockerfile
@@ -71,10 +71,18 @@
       llvm \
       ninja-build \
       pkg-config \
+      unzip \
       valgrind \
       vim
 ENV PATH /usr/lib/llvm-6.0/bin:$PATH
 
+# lib/as3 (ActionScript)
+RUN mkdir -p /usr/local/adobe/flex/4.6 && \
+    cd /usr/local/adobe/flex/4.6 && \
+    wget -q "http://download.macromedia.com/pub/flex/sdk/flex_sdk_4.6.zip" && \
+    unzip flex_sdk_4.6.zip
+ENV FLEX_HOME /usr/local/adobe/flex/4.6
+
 RUN apt-get install -y --no-install-recommends \
 `# C++ dependencies` \
       libboost-all-dev \