diff --git a/Makefile b/Makefile
index 84cea1c951..242265f2cf 100644
--- a/Makefile
+++ b/Makefile
@@ -192,6 +192,7 @@ unexport CPP
 unexport CFLAGS
 unexport CXXFLAGS
 unexport GREP_OPTIONS
+unexport CONFIG_SITE
 
 GNU_HOST_NAME:=$(shell support/gnuconfig/config.guess)