diff --git a/firmware/Makefile b/firmware/Makefile
index 19adbf4..21aa3f9 100644
--- a/firmware/Makefile
+++ b/firmware/Makefile
@@ -4,7 +4,7 @@ DEVICETREE_GEN_DIR=.
 cpu: soc.py
 	python3 soc.py
 clean:
-	rm -rf build csr.json overlay.config overlay.dts
+	rm -rf build csr.json overlay.config overlay.dts pin_io.h
 overlay.dts overlay.config: csr.json litex_json2dts_zephyr.py
 	# NOTE: Broken in LiteX 2022.4.
 	$(DEVICETREE_GEN_DIR)/litex_json2dts_zephyr.py --dts overlay.dts --config overlay.config csr.json