diff --git a/.appveyor.yml b/.appveyor.yml
index db383ff5..c4b866b0 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -46,7 +46,7 @@ test_script:
 
         cd cmake-build
 
-        cmake -G "Visual Studio 15 2017" -DCMAKE_BUILD_TYPE=$env:$env:configuration ../
+        cmake -G "Visual Studio 15 2017" -DCMAKE_BUILD_TYPE=$env:configuration ../
 
         msbuild /t:Build cryptopp-static.vcxproj
 
@@ -66,7 +66,7 @@ test_script:
 
         cd cmake-build
 
-        cmake -G "Visual Studio 14 2015" -DCMAKE_BUILD_TYPE=$env:$env:configuration ../
+        cmake -G "Visual Studio 14 2015" -DCMAKE_BUILD_TYPE=$env:configuration ../
 
         msbuild /t:Build cryptopp-static.vcxproj
 
@@ -86,7 +86,7 @@ test_script:
 
         cd cmake-build
 
-        cmake -G "Visual Studio 12 2013" -DCMAKE_BUILD_TYPE=$env:$env:configuration ../
+        cmake -G "Visual Studio 12 2013" -DCMAKE_BUILD_TYPE=$env:configuration ../
 
         msbuild /t:Build cryptopp-static.vcxproj