diff --git a/variables.mk b/variables.mk
index f0bdf634..a0c6a9af 100644
--- a/variables.mk
+++ b/variables.mk
@@ -125,7 +125,6 @@ HARNESS_SMEMS_FILE ?= $(build_dir)/$(long_name).harness.mems.v
 HARNESS_SMEMS_CONF ?= $(build_dir)/$(long_name).harness.mems.conf
 HARNESS_SMEMS_FIR  ?= $(build_dir)/$(long_name).harness.mems.fir
 
-sim_files                  ?= $(build_dir)/sim_files.f
 sim_files                  ?= $(build_dir)/sim_files.f
 sim_top_blackboxes         ?= $(build_dir)/firrtl_black_box_resource_files.top.f
 sim_harness_blackboxes     ?= $(build_dir)/firrtl_black_box_resource_files.harness.f