diff --git a/Makefile b/Makefile
index 355a404..50a9f62 100644
--- a/Makefile
+++ b/Makefile
@@ -419,6 +419,8 @@
 unexport MACHINE
 unexport O
 unexport GCC_COLORS
+unexport PLATFORM
+unexport OS
 
 GNU_HOST_NAME := $(shell support/gnuconfig/config.guess)