diff --git a/CMakeLists.txt b/CMakeLists.txt
index 271e93c..f5b3094 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -149,7 +149,9 @@ set(GR_INCLUDE_DIR include)
set(GR_DATA_DIR share)
set(GR_PKG_DATA_DIR ${GR_DATA_DIR}/${CMAKE_PROJECT_NAME})
set(GR_DOC_DIR ${GR_DATA_DIR}/doc)
-set(GR_PKG_DOC_DIR ${GR_DOC_DIR}/${CMAKE_PROJECT_NAME}-${DOCVER})
+if (NOT GR_PKG_DOC_DIR)
+ set(GR_PKG_DOC_DIR ${GR_DOC_DIR}/${CMAKE_PROJECT_NAME}-${DOCVER})
+endif()
set(GR_CONF_DIR etc)
set(GR_PKG_CONF_DIR ${GR_CONF_DIR}/${CMAKE_PROJECT_NAME}/conf.d)
set(GR_LIBEXEC_DIR libexec)