diff --git a/cpprules.in b/cpprules.in
index b8857bae..12964fa8 100644
--- a/cpprules.in
+++ b/cpprules.in
@@ -24,6 +24,5 @@ CPP_SED_MAGIC = $(SED) -e '/^\#  *[0-9][0-9]*  *.*$$/d' \
                        -e '/^[         ]*XHASH/s/XHASH/\#/' \
                        -e '/\@\@$$/s/\@\@$$/\\/'
 
-# Allow people to comment out lines by starting them with '##'
 .pre:
-	$(SED) -e '/^\#\#/d' $< | $(RAWCPP) $(RAWCPPFLAGS) $(CPP_FILES_FLAGS) | $(CPP_SED_MAGIC) > $@
+	$(RAWCPP) $(RAWCPPFLAGS) $(CPP_FILES_FLAGS) < $< | $(CPP_SED_MAGIC) > $@