diff --git a/exec/GNUmakefile b/exec/GNUmakefile
index 6c6125ef1fccc7432b9fabdd45e7b32b24e6bb85..4b82a81bf8c0ac5db701421aa8b1ba68bbdcae6c 100644
--- a/exec/GNUmakefile
+++ b/exec/GNUmakefile
@@ -44,3 +44,14 @@ all : 	bullseye.bin \
 
 %.bin : %.src $(BAJAPATH)
 	@$(BAJAPATH) /q $<
+
+devel : tags cscope.out
+
+tags: cscope.files
+	exctags -VL cscope.files
+
+cscope.out: cscope.files
+	cscope -b
+
+cscope.files::
+	find . -name '*.js' > cscope.files