diff --git a/ports/py-lxml/portfile.cmake b/ports/py-lxml/portfile.cmake
index db9660e..10d4ad9 100644
--- a/ports/py-lxml/portfile.cmake
+++ b/ports/py-lxml/portfile.cmake
@@ -5,7 +5,9 @@ vcpkg_from_pythonhosted(
     SHA512          7f8a3717645893bc6f790cc9adfb8fdab91c352dc4dc23c0ccb4af9a0d138acf9ef5054e9786af497955f10079e9242dbd63ea9ac39c33bfd71ca2fe4ef4a7c0
 )
 
-set(ENV{INCLUDE} "${CURRENT_INSTALLED_DIR}/include;$ENV{INCLUDE}")
+if(VCPKG_TARGET_IS_WINDOWS)
+  set(ENV{INCLUDE} "${CURRENT_INSTALLED_DIR}/include;$ENV{INCLUDE}")
+endif()
 
 vcpkg_python_build_and_install_wheel(SOURCE_PATH "${SOURCE_PATH}")