diff --git a/postplug.d/10filesystems b/postplug.d/10filesystems
index baa484c..0292c68 100644
--- a/postplug.d/10filesystems
+++ b/postplug.d/10filesystems
@@ -173,7 +173,7 @@ blkid | while read line; do
    [ "$label" ] || label="disk"
    if [ -e $dev ]; then
       # skip removable partitions
-      udisks --show-info $dev | grep "system internal:[[:space:]]*0$" || {
+      [ "`udisks --show-info $dev | grep 'system internal:[[:space:]]*0$'`" ] && {
          [ "$DEBUG" ] && logmsg "$me" $"skipped device $dev ($uuid): removable"
 	 continue;
       }