diff --git a/.appveyor.yml b/.appveyor.yml
index 6465b93..c2fffb5 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -29,5 +29,5 @@ install:
 build_script:
   - mkdir build
   - cd build 
-  - cmake .. -DZLIB_INCLUDE_DIR=..\deps\zlib -DZLIB_LIBRARY=..\deps\zlib\debug\zlibd.lib -DPNG_INCLUDE_DIR=..\deps\libpng -DPNG_LIBRARIES=..\deps\libpng\debug\libpng16d.lib
+  - cmake .. -DZLIB_INCLUDE_DIR=..\deps\zlib -DZLIB_LIBRARY=..\deps\zlib\debug\zlibd.lib -DPNG_PNG_INCLUDE_DIR=..\deps\libpng -DPNG_LIBRARY=..\deps\libpng\debug\libpng16d.lib
   - cmake --build .