-AMADDR = ActiveMessageAddressC\$$addr
-# Uncomment the next two lines if you have a toolchain without the dollar sign
-# patch. This needs nesc 1.2.8 or newer (1.2.9 is recommended).
-#PFLAGS += -fnesc-separator=__
-#AMADDR = ActiveMessageAddressC__addr
+# Use __ as the separator - requires nesC 1.2.9 or later
+ifneq ($(filter sim,$(GOALS)),sim)
+ifneq ($(filter sim-sf,$(GOALS)),sim-sf)
+ PFLAGS += -fnesc-separator=__
+endif
+endif
+AMADDR = ActiveMessageAddressC__addr