diff --git a/vlsi/Makefile b/vlsi/Makefile
index b3901fe6..074ec66a 100644
--- a/vlsi/Makefile
+++ b/vlsi/Makefile
@@ -42,7 +42,7 @@ HAMMER_EXEC        ?= $(if $(filter $(tech_name),sky130),\
                         ./example-vlsi-sky130,\
                         ./example-vlsi)
 VLSI_TOP           ?= $(TOP)
-VLSI_MODEL_DUT_NAME ?= chiptop
+VLSI_MODEL_DUT_NAME ?= chiptop0
 # If overriding, this should be relative to $(vlsi_dir)
 VLSI_OBJ_DIR       ?= build
 ifneq ($(CUSTOM_VLOG),)
diff --git a/vlsi/sim.mk b/vlsi/sim.mk
index ea2c76d7..1da6f0bc 100644
--- a/vlsi/sim.mk
+++ b/vlsi/sim.mk
@@ -51,7 +51,11 @@ $(SIM_DEBUG_CONF): $(sim_common_files) check-binary
 	mkdir -p $(dir $@)
 	mkdir -p $(output_dir)
 	echo "sim.inputs:" > $@
-	echo "  defines: ['DEBUG']" >> $@
+	echo "  defines:" >> $@
+	echo "    - 'DEBUG'" >> $@;
+ifndef USE_VPD
+	echo "    - 'FSDB=1'" >> $@;
+endif
 	echo "  defines_meta: 'append'" >> $@
 	echo "  execution_flags:" >> $@
 	for x in $(VERBOSE_FLAGS) $(call get_waveform_flag,$(call get_sim_out_name,$(BINARY))); do \