diff --git a/.appveyor.yml b/.appveyor.yml
index 51dc759..85b63fc 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -1,8 +1,8 @@
 environment:
   RUST_BACKTRACE: 1
-  OPENSSL_DIR "C:\Tools\vcpkg\packages\openssl-windows_x64-windows"
-  BSON_LIB "C:\Tools\vcpkg\packages\libbson_x64-windows\lib"
-  MONGO_LIB "C:\Tools\vcpkg\packages\mongo-c-driver_x64-windows\lib"
+  OPENSSL_DIR: C:\Tools\vcpkg\packages\openssl-windows_x64-windows
+  BSON_LIB: C:\Tools\vcpkg\packages\libbson_x64-windows\lib
+  MONGO_LIB: C:\Tools\vcpkg\packages\mongo-c-driver_x64-windows\lib
   matrix:
   - TARGET: x86_64-pc-windows-msvc
 install: