diff --git a/mk/config.mk.in b/mk/config.mk.in
index ab4fd5acbac769874727b57968faef1e0d433554..27c9ffcb43b4d525718a6c03d754147c8fae8e4c 100644
--- a/mk/config.mk.in
+++ b/mk/config.mk.in
@@ -529,7 +529,7 @@ CONTEXT_DIFF		= @ContextDiffCmd@
 CP			= cp
 CPP			= @CPP@
 CTAGS 			= $(ETAGS)
-RAWCPP                  = @RAWCPP@
+RAWCPP                  = $(CPP) -undef -traditional
 INSTALL			= @INSTALL@
 #
 # Sigh - the autoconf macro for INSTALL will subst a relative path to the fallback