diff --git a/hotp/Makefile b/hotp/Makefile
index 3b9a8dc..4f97c4b 100644
--- a/hotp/Makefile
+++ b/hotp/Makefile
@@ -6,7 +6,7 @@
 
 .PHONY: all
 all:
-	$(MAKE) -C host CROSS_COMPILE="$(HOST_CROSS_COMPILE)"
+	$(MAKE) -C host CROSS_COMPILE="$(HOST_CROSS_COMPILE)" --no-builtin-variables
 	$(MAKE) -C ta CROSS_COMPILE="$(TA_CROSS_COMPILE)"
 
 .PHONY: clean