diff --git a/src/ec/google/chromeec/Makefile.inc b/src/ec/google/chromeec/Makefile.inc
index 93ffe8f448..590ad114c1 100644
--- a/src/ec/google/chromeec/Makefile.inc
+++ b/src/ec/google/chromeec/Makefile.inc
@@ -54,8 +54,10 @@ pdrw.hash-file := $(obj)/mainboard/$(MAINBOARDDIR)/pdrw.hash
 pdrw.hash-name := pdrw.hash
 pdrw.hash-type := raw
 
+CHROMEEC_SOURCE ?= $(top)/3rdparty/chromeec
+
 $(obj)/mainboard/$(MAINBOARDDIR)/ecrw:
-	$(MAKE) -C $(top)/3rdparty/chromeec \
+	$(MAKE) -C $(CHROMEEC_SOURCE) \
 		out=$(abspath $(obj)/external/chromeec/$(CONFIG_EC_GOOGLE_CHROMEEC_BOARDNAME)) \
 		CROSS_COMPILE=$(subst -cpp,-,$(CPP_arm)) \
 		HOST_CROSS_COMPILE= \
@@ -64,7 +66,7 @@ $(obj)/mainboard/$(MAINBOARDDIR)/ecrw:
 	cp $(obj)/external/chromeec/$(CONFIG_EC_GOOGLE_CHROMEEC_BOARDNAME)/RW/ec.RW.flat $@
 
 $(obj)/mainboard/$(MAINBOARDDIR)/pdrw:
-	$(MAKE) -C $(top)/3rdparty/chromeec \
+	$(MAKE) -C $(CHROMEEC_SOURCE) \
 		out=$(abspath $(obj)/external/chromeec/$(CONFIG_EC_GOOGLE_CHROMEEC_PD_BOARDNAME)) \
 		CROSS_COMPILE=$(subst -cpp,-,$(CPP_arm)) \
 		HOST_CROSS_COMPILE= \