diff --git a/make/rules.mk b/make/rules.mk
index ebeb8072..7bd6c16a 100644
--- a/make/rules.mk
+++ b/make/rules.mk
@@ -313,3 +313,9 @@ echo-development:
 
 echo-libpath:
 	@echo LD_LIBRARY_PATH = $(LD_LIBRARY_PATH)
+
+trace-marks:
+	for f in $(ALL_CPP); do \
+		sed 's/^{$$/{_/' $$f > $$f.rep ;\
+		cp $$f.rep $$f ;\
+	done