--- Modules/Platform/Darwin.cmake
+++ Modules/Platform/Darwin.cmake
@@ -265,7 +265,9 @@
     endforeach()
   endif()
 endif()
-list(APPEND CMAKE_SYSTEM_PREFIX_PATH
-  /sw        # Fink
-  /opt/local # MacPorts
-  )
+
+# prepend the MacPorts prefix to CMAKE_SYSTEM_PREFIX_PATH
+# might already exist after this if the user has specified it
+list(INSERT CMAKE_SYSTEM_PREFIX_PATH 0
+  __PREFIX__
+)
--- Modules/Platform/UnixPaths.cmake
+++ Modules/Platform/UnixPaths.cmake
@@ -37,7 +37,7 @@
 # synchronized
 list(APPEND CMAKE_SYSTEM_PREFIX_PATH
   # Standard
-  /usr/local /usr /
+  /usr /
   )
 if(_CMAKE_INSTALL_DIR)
   list(APPEND CMAKE_SYSTEM_PREFIX_PATH