diff --git a/appveyor.yml b/appveyor.yml
index cbb8df2a6..a16967d6b 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -3,31 +3,35 @@ branches:
   only:
   - master
   - RC_1_1
-os: Previous Visual Studio 2015
 clone_depth: 1
 environment:
   matrix:
   - variant: test_debug
     compiler: msvc-14.0
+    os: Visual Studio 2015
     sim: 1
     linkflags: '"/LIBPATH:C:\\openssl-1.0.1p-vs2015\\lib"'
     include: '"c:\\openssl-1.0.1p-vs2015\\include"'
   - variant: test_debug
     compiler: msvc-12.0
+    os: Visual Studio 2013
     x64: 1
     linkflags: '"/LIBPATH:C:\\openssl-1.0.1p-vs2013\\lib64"'
     include: '"c:\\openssl-1.0.1p-vs2013\\include"'
   - variant: test_debug
     python_package: 1
     compiler: msvc-10.0
+    os: Visual Studio 2015
     linkflags: '"/LIBPATH:C:\\openssl-1.0.1p-vs2010\\lib"'
     include: '"c:\\openssl-1.0.1p-vs2010\\include"'
   - variant: test_barebones
     compiler: msvc-12.0
+    os: Visual Studio 2013
     linkflags: '"/LIBPATH:C:\\openssl-1.0.1p-vs2013\\lib"'
     include: '"c:\\openssl-1.0.1p-vs2013\\include"'
   - variant: test_release
     compiler: msvc-12.0
+    os: Visual Studio 2013
     linkflags: '"/LIBPATH:C:\\openssl-1.0.1p-vs2013\\lib"'
     include: '"c:\\openssl-1.0.1p-vs2013\\include"'