diff --git a/documentation/CMakeLists.txt b/documentation/CMakeLists.txt
index e143348d..4ae5b49a 100644
--- a/documentation/CMakeLists.txt
+++ b/documentation/CMakeLists.txt
@@ -24,7 +24,7 @@ configure_file(${CMAKE_CURRENT_LIST_DIR}/conf.py ${CMAKE_CURRENT_BINARY_DIR}/con
 add_custom_target(
   GenerateDocs
   ${CMAKE_COMMAND} -E make_directory "${DOXYGEN_OUTPUT_DIRECTORY}"
-  COMMAND "${MCSS_SOURCE_DIR}/documentation/doxygen.py" "${CMAKE_CURRENT_BINARY_DIR}/conf.py"
+  COMMAND "${m.css_SOURCE_DIR}/documentation/doxygen.py" "${CMAKE_CURRENT_BINARY_DIR}/conf.py"
   COMMAND echo "Docs written to: ${DOXYGEN_OUTPUT_DIRECTORY}"
   WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}"
 )