diff --git a/tools/building.py b/tools/building.py
index bb0fcdcb654280c70bf0d50b23c95ed9042bd28c..3c2dbc4e7498524181b4287f886513e59d25f9ff 100644
--- a/tools/building.py
+++ b/tools/building.py
@@ -435,12 +435,6 @@ def DoBuilding(target, objects):
 
                 break
     else:
-        # merge the repeated items in the Env
-        if Env.has_key('CPPPATH')   : Env['CPPPATH'] = list(set(Env['CPPPATH']))
-        if Env.has_key('CPPDEFINES'): Env['CPPDEFINES'] = list(set(Env['CPPDEFINES']))
-        if Env.has_key('LIBPATH')   : Env['LIBPATH'] = list(set(Env['LIBPATH']))
-        if Env.has_key('LIBS')      : Env['LIBS'] = list(set(Env['LIBS']))
-
         program = Env.Program(target, objects)
 
     EndBuilding(target, program)