--- 50mounted-tests	2014-01-13 09:15:49.242758975 -0500
+++ 50mounted-tests	2014-01-13 09:18:03.236983860 -0500
@@ -5,8 +5,7 @@
 
 . /usr/share/os-prober/common.sh
 
-types="$(fs_type "$partition")" || types=NOT-DETECTED
-if [ "$types" = NOT-DETECTED ]; then
+if ! types="$(fs_type "$partition")" || [ -z "$types" ]; then
 	debug "$1 type not recognised; skipping"
 	exit 0
 elif [ "$types" = swap ]; then