diff --git a/npc/Makefile b/npc/Makefile
index 8e1d233..0ad9d4a 100644
--- a/npc/Makefile
+++ b/npc/Makefile
@@ -2,6 +2,7 @@ VSRC := $(wildcard vsrc/*.v)
 CPPSRC := $(addprefix $(PWD)/,$(wildcard csrc/*.cpp))
 PREFIX ?= build
 OBJDIR := $(PREFIX)/obj
+VERILATOR_FLAGS := --cc --exe
 
 all: $(OBJDIR)
 	$(MAKE) -j -C $(OBJDIR) -f Vexample.mk Vexample
@@ -10,8 +11,9 @@ sim: all
 	$(call git_commit, "sim RTL") # DO NOT REMOVE THIS LINE!!!
 	@echo "Running" $(OBJDIR)/Vexample "..."
 	@echo "================================"
-	@$(OBJDIR)/Vexample +trace off
+	@$(OBJDIR)/Vexample +tracing_off
 
+trace: VERILATOR_FLAGS += --trace
 trace: all
 	$(call git_commit, "trace RTL") # DO NOT REMOVE THIS LINE!!!
 	@$(OBJDIR)/Vexample
@@ -19,7 +21,7 @@ trace: all
 
 $(OBJDIR): $(VSRC) $(CPPSRC)
 	mkdir -p $(OBJDIR)
-	verilator --trace --cc --exe --Mdir $(PWD)/$(OBJDIR) $(VSRC) $(CPPSRC)
+	verilator $(VERILATOR_FLAGS) --Mdir $(PWD)/$(OBJDIR) $(VSRC) $(CPPSRC)
 
 include ../Makefile