diff --git a/CMakeLists.txt b/CMakeLists.txt
index c5c2f7531..4e16a95de 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -197,11 +197,11 @@ endif()
 if(NOT WIN32 AND NOT APPLE)
     if(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
         if(${CMAKE_SYSTEM_NAME} MATCHES "Linux")
-            set(CMAKE_INSTALL_PREFIX "/usr")
+            set(CMAKE_INSTALL_PREFIX "/usr" CACHE INTERNAL "CMAKE_INSTALL_PREFIX")
         elseif(${CMAKE_SYSTEM_NAME} MATCHES "NetBSD")
-            set(CMAKE_INSTALL_PREFIX "/usr/pkg")
+            set(CMAKE_INSTALL_PREFIX "/usr/pkg" CACHE INTERNAL "CMAKE_INSTALL_PREFIX")
         else()
-            set(CMAKE_INSTALL_PREFIX "/usr/local")
+            set(CMAKE_INSTALL_PREFIX "/usr/local" CACHE INTERNAL "CMAKE_INSTALL_PREFIX")
         endif()
     endif()
     message("-- Installation prefix is set to " ${CMAKE_INSTALL_PREFIX})