--- a/docs/doxygen/CMakeLists.txt
+++ b/docs/doxygen/CMakeLists.txt
@@ -50,4 +50,4 @@
 
 add_custom_target(doxygen_target ALL DEPENDS ${BUILT_DIRS})
 
-install(DIRECTORY ${BUILT_DIRS} DESTINATION ${GR_PKG_DOC_DIR})
+install(DIRECTORY ${BUILT_DIRS} DESTINATION ${CMAKE_INSTALL_DOCDIR})