Forgot to add .cxx and .cpp to the second case statement.
Thanks to Daniel Larsson.
diff --git a/Modules/makesetup b/Modules/makesetup
index 47c8dbe..83fdc21 100755
--- a/Modules/makesetup
+++ b/Modules/makesetup
@@ -170,6 +170,8 @@
 			*.cc)  obj=`basename $src .cc`.o; cc='$(CCC)';;
 			*.c++) obj=`basename $src .c++`.o; cc='$(CCC)';;
 			*.C)   obj=`basename $src .C`.o; cc='$(CCC)';;
+			*.cxx) obj=`basename $src .cxx`.o; cc='$(CCC)';;
+			*.cpp) obj=`basename $src .cpp`.o; cc='$(CCC)';;
 			*)     continue;;
 			esac
 			objs="$objs $obj"