diff --git a/BaseBuild/Basesys/gmp b/BaseBuild/Basesys/gmp
index 5517e84..adf1505 100644
--- a/BaseBuild/Basesys/gmp
+++ b/BaseBuild/Basesys/gmp
@@ -129,7 +129,7 @@ postmk() {
 	rm -r ../build-gmp
 	if [ $MK64BIT == "true" ]; then
 		mv -v $TMPROOT/usr/include/gmp{,-64}.h
-		cat > /usr/include/gmp.h << "EOF"
+		cat > $TMPROOT/usr/include/gmp.h << "EOF"
 /* gmp.h - Stub Header */
 #ifndef __STUB__GMP_H__
 #define __STUB__GMP_H__