diff --git a/firmware/Makefile b/firmware/Makefile
index f912515..d1e1f7c 100644
--- a/firmware/Makefile
+++ b/firmware/Makefile
@@ -1,7 +1,10 @@
 .PHONY: cpu clean
+
+DEVICETREE_GEN_DIR=.
 cpu: soc.py
 	python3 soc.py
 clean:
 	rm -rf build csr.json overlay.config overlay.dts
-overlay.dts overlay.config: csr.json
+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