diff --git a/rules/pulpos/default_rules.mk b/rules/pulpos/default_rules.mk
index 2f0edfc..a27c6d5 100644
--- a/rules/pulpos/default_rules.mk
+++ b/rules/pulpos/default_rules.mk
@@ -153,7 +153,13 @@ endif
 # VERILATOR Flags
 #
 verilator_flags ?= --trace
+ifdef bootmode
+ifeq ($(bootmode), fast_debug)
+verilator_flags += +bootmode=fast_debug_preload
+else
 verilator_flags += +bootmode=jtag
+endif
+endif
 verilator_flags += +log_file=trace_core.log +itb_file=$(TARGETS).itb
 
 #