diff --git a/common.mk b/common.mk
index 820b6d44..43340615 100644
--- a/common.mk
+++ b/common.mk
@@ -102,6 +102,7 @@ $(BOOTROM_TARGETS): $(build_dir)/bootrom.%.img: $(TESTCHIP_RSRCS_DIR)/testchipip
 #########################################################################################
 # AG: must re-elaborate if cva6 sources have changed... otherwise just run firrtl compile
 $(FIRRTL_FILE) $(ANNO_FILE) &: $(SCALA_SOURCES) $(sim_files) $(SCALA_BUILDTOOL_DEPS) $(EXTRA_GENERATOR_REQS)
+	if [ -d $(OUT_DIR) ]; then rm -rf $(OUT_DIR); fi
 	mkdir -p $(build_dir)
 	$(call run_scala_main,$(SBT_PROJECT),$(GENERATOR_PACKAGE).Generator,\
 		--target-dir $(build_dir) \