diff --git a/Shorewall/install.sh b/Shorewall/install.sh
index abe6498b5..9693cc35a 100755
--- a/Shorewall/install.sh
+++ b/Shorewall/install.sh
@@ -135,7 +135,7 @@ case $(uname) in
 	[ -z "$OWNER" ] && OWNER=root
 	[ -z "$GROUP" ] && GROUP=wheel
 	MAC=Yes
-	SPARSE=Yes
+	[ -z "${PREFIX}" && SPARSE=Yes
 	INSTALLD=
 	;;	
     *)