vcpkg_fixup_pkgconfig.cmake.diff

diff --git a/scripts/cmake/vcpkg_fixup_pkgconfig.cmake b/scripts/cmake/vcpkg_fixup_pkgconfig.cmake
index baccef100..7f0dc464d 100644
--- a/scripts/cmake/vcpkg_fixup_pkgconfig.cmake
+++ b/scripts/cmake/vcpkg_fixup_pkgconfig.cmake
@@ -50,8 +50,8 @@ function(vcpkg_fixup_pkgconfig_check_files pkg_cfg_cmd _file _config _system_lib
     set(PKGCONFIG_PACKAGES_DIR "${_VCPKG_PACKAGES_PKGCONF}${PATH_SUFFIX_${_config}}/lib/pkgconfig")
     set(PKGCONFIG_PACKAGES_SHARE_DIR "${_VCPKG_PACKAGES_PKGCONF}/share/pkgconfig")
 
-    if(ENV{PKG_CONFIG_PATH})
-        set(BACKUP_ENV_PKG_CONFIG_PATH_${_config} $ENV{PKG_CONFIG_PATH})
+    if(DEFINED ENV{PKG_CONFIG_PATH})
+        set(BACKUP_ENV_PKG_CONFIG_PATH_${_config} "$ENV{PKG_CONFIG_PATH}")
         set(ENV{PKG_CONFIG_PATH} "${PKGCONFIG_INSTALLED_DIR}${VCPKG_HOST_PATH_SEPARATOR}${PKGCONFIG_INSTALLED_SHARE_DIR}${VCPKG_HOST_PATH_SEPARATOR}${PKGCONFIG_PACKAGES_DIR}${VCPKG_HOST_PATH_SEPARATOR}${PKGCONFIG_PACKAGES_SHARE_DIR}${VCPKG_HOST_PATH_SEPARATOR}$ENV{PKG_CONFIG_PATH}")
     else()
         set(ENV{PKG_CONFIG_PATH} "${PKGCONFIG_INSTALLED_DIR}${VCPKG_HOST_PATH_SEPARATOR}${PKGCONFIG_INSTALLED_SHARE_DIR}${VCPKG_HOST_PATH_SEPARATOR}${PKGCONFIG_PACKAGES_DIR}${VCPKG_HOST_PATH_SEPARATOR}${PKGCONFIG_PACKAGES_SHARE_DIR}")
@@ -237,6 +237,12 @@ function(vcpkg_fixup_pkgconfig_check_files pkg_cfg_cmd _file _config _system_lib
     endforeach()
 
     set(CMAKE_FIND_LIBRARY_SUFFIXES ${CMAKE_FIND_LIBRARY_SUFFIXES_BACKUP})
+    if(DEFINED BACKUP_ENV_PKG_CONFIG_PATH_${_config})
+        set(ENV{PKG_CONFIG_PATH} "${BACKUP_ENV_PKG_CONFIG_PATH_${_config}}")
+        unset(BACKUP_ENV_PKG_CONFIG_PATH_${_config})
+    else()
+        unset(ENV{PKG_CONFIG_PATH})
+    endif()
 endfunction()
 
 function(vcpkg_fixup_pkgconfig)