diff --git a/appveyor.yml b/appveyor.yml
index 7dde6d68..5dddf7dd 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -33,10 +33,10 @@ build_script:
 - cmake --build . --config Release
 - cd ..
 - cd ..
-- appveyor DownloadFile http://zlib.net/zlib-1.2.10.tar.gz -FileName zlib-1.2.10.tar.gz
-- 7z x zlib-1.2.10.tar.gz > NUL
-- 7z x zlib-1.2.10.tar > NUL
-- cd zlib-1.2.10
+- appveyor DownloadFile http://zlib.net/zlib-1.2.11.tar.gz -FileName zlib-1.2.11.tar.gz
+- 7z x zlib-1.2.11.tar.gz > NUL
+- 7z x zlib-1.2.11.tar > NUL
+- cd zlib-1.2.11
 - md build
 - cd build
 - cmake -G %msvc% ..
@@ -46,9 +46,9 @@ build_script:
 - cd ..
 - md build
 - cd build
-- cmake -G %msvc% %cpp11% %boost% %x3_parse%  -DMSGPACK_BOOST_DIR=C:\Libraries\\boost_1_60_0 -DGTEST_LIBRARY=%APPVEYOR_BUILD_FOLDER%\googletest-release-1.7.0\build\Release\gtest.lib -DGTEST_MAIN_LIBRARY=%APPVEYOR_BUILD_FOLDER%\googletest-release-1.7.0\build\Release\gtest_main.lib -DGTEST_INCLUDE_DIR=%APPVEYOR_BUILD_FOLDER%\googletest-release-1.7.0\include -DZLIB_LIBRARY=%APPVEYOR_BUILD_FOLDER%\zlib-1.2.10\build\Release\zlib.lib -DZLIB_INCLUDE_DIR=%APPVEYOR_BUILD_FOLDER%\zlib-1.2.10 -DCMAKE_CXX_FLAGS='"/D_VARIADIC_MAX=10 /EHsc"' ..
+- cmake -G %msvc% %cpp11% %boost% %x3_parse%  -DMSGPACK_BOOST_DIR=C:\Libraries\\boost_1_60_0 -DGTEST_LIBRARY=%APPVEYOR_BUILD_FOLDER%\googletest-release-1.7.0\build\Release\gtest.lib -DGTEST_MAIN_LIBRARY=%APPVEYOR_BUILD_FOLDER%\googletest-release-1.7.0\build\Release\gtest_main.lib -DGTEST_INCLUDE_DIR=%APPVEYOR_BUILD_FOLDER%\googletest-release-1.7.0\include -DZLIB_LIBRARY=%APPVEYOR_BUILD_FOLDER%\zlib-1.2.11\build\Release\zlib.lib -DZLIB_INCLUDE_DIR=%APPVEYOR_BUILD_FOLDER%\zlib-1.2.11 -DCMAKE_CXX_FLAGS='"/D_VARIADIC_MAX=10 /EHsc"' ..
 - cmake --build . --config Release
 
 test_script:
-- set PATH=%PATH%;%APPVEYOR_BUILD_FOLDER%\googletest-release-1.7.0\build\Release;%APPVEYOR_BUILD_FOLDER%\zlib-1.2.10\build\Release;%APPVEYOR_BUILD_FOLDER%\build\release
+- set PATH=%PATH%;%APPVEYOR_BUILD_FOLDER%\googletest-release-1.7.0\build\Release;%APPVEYOR_BUILD_FOLDER%\zlib-1.2.11\build\Release;%APPVEYOR_BUILD_FOLDER%\build\release
 - ctest -V