--- gcc/configure.orig	2017-12-09 14:33:36.570113000 -0800
+++ gcc/configure	2017-12-09 14:33:50.647310000 -0800
@@ -11803,7 +11803,7 @@
 	CC="${CC_FOR_BUILD}" CFLAGS="${CFLAGS_FOR_BUILD}" \
 	CXX="${CXX_FOR_BUILD}" CXXFLAGS="${CXXFLAGS_FOR_BUILD}" \
 	LD="${LD_FOR_BUILD}" LDFLAGS="${LDFLAGS_FOR_BUILD}" \
-	GMPINC="" CPPFLAGS="${CPPFLAGS} -DGENERATOR_FILE" \
+	GMPINC="" CPPFLAGS="${CPPFLAGS_FOR_BUILD} -DGENERATOR_FILE" \
 	${realsrcdir}/configure \
 		--enable-languages=${enable_languages-all} \
 		--target=$target_alias --host=$build_alias --build=$build_alias
