diff --git a/CMakeLists.txt b/CMakeLists.txt
index d64ee41..e33e7bf 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -76,4 +76,4 @@ add_subdirectory(src)
 add_subdirectory(doc) 
 
 # here we specify the installation directory
-set(CMAKE_INSTALL_PREFIX ${RTTR_INSTALL_DIR} CACHE PATH  "RTTR install prefix" FORCE)
+set(CMAKE_INSTALL_PREFIX ${RTTR_INSTALL_DIR} CACHE PATH  "RTTR install prefix")