diff --git a/build/docker/msvc2017/Dockerfile b/build/docker/msvc2017/Dockerfile
index 7da895c..a2b3cd7 100644
--- a/build/docker/msvc2017/Dockerfile
+++ b/build/docker/msvc2017/Dockerfile
@@ -31,7 +31,7 @@
 RUN DEL C:\TEMP\vs_buildtools.exe
 
 # Install CMake
-ADD https://github.com/Kitware/CMake/releases/download/v3.13.2/cmake-3.13.2-win64-x64.msi C:\TEMP\cmake.msi
+ADD https://github.com/Kitware/CMake/releases/download/v3.13.4/cmake-3.13.4-win64-x64.msi C:\TEMP\cmake.msi
 RUN msiexec.exe /i C:\TEMP\cmake.msi /qn && `
     SETX PATH "%PATH%;C:\Program Files\CMake\bin" && `
     DEL C:\TEMP\cmake.msi
@@ -89,8 +89,15 @@
 # Install python3
 RUN choco install python3 -y
 
+# Install Adobe Flex 4.6 SDK and set FLEX_HOME so it can be found
+ADD http://download.macromedia.com/pub/flex/sdk/flex_sdk_4.6.zip C:\Adobe\Flex\SDK\4.6\SDK.zip
+RUN CD C:\Adobe\Flex\SDK\4.6 && `
+    7z x SDK.zip && `
+    DEL SDK.zip && `
+    SETX FLEX_HOME "C:\Adobe\Flex\SDK\4.6"
+
 # Start developer command prompt with any other commands specified.
 ENTRYPOINT C:\BuildTools\Common7\Tools\VsDevCmd.bat -arch=amd64 &&
 
 # Default to PowerShell if no other command specified.
-CMD ["powershell.exe", "-NoLogo", "-ExecutionPolicy", "Bypass"]
\ No newline at end of file
+CMD ["powershell.exe", "-NoLogo", "-ExecutionPolicy", "Bypass"]
diff --git a/build/docker/msvc2017/build.bat b/build/docker/msvc2017/build.bat
index ac7b68a..018805b 100644
--- a/build/docker/msvc2017/build.bat
+++ b/build/docker/msvc2017/build.bat
@@ -28,6 +28,7 @@
 cmake^
   -DBOOST_ROOT=C:\Libraries\boost_1_69_0^
   -DBOOST_LIBRARYDIR=C:\Libraries\boost_1_69_0\lib64-msvc-14.1^
+  -DFLEX_HOME=C:\Adobe\Flex\SDK\4.6^
   -DLIBEVENT_ROOT=C:\Libraries\libevent-2.1.8^
   -DZLIB_ROOT=C:\Libraries\zlib-1.2.11^
   -DCMAKE_BUILD_TYPE=Release^
@@ -41,4 +42,4 @@
 cmake --build . --target check || EXIT /B
 
 :: Install
-cmake --build . --target install
\ No newline at end of file
+cmake --build . --target install