diff --git a/rules/rules.d/60-persistent-storage.rules b/rules/rules.d/60-persistent-storage.rules
index 64e957890..1b85156cc 100644
--- a/rules/rules.d/60-persistent-storage.rules
+++ b/rules/rules.d/60-persistent-storage.rules
@@ -61,7 +61,9 @@ ENV{DEVTYPE}=="partition", ENV{ID_PATH}=="?*", SYMLINK+="disk/by-path/$env{ID_PA
 ENV{DEVTYPE}=="disk", KERNEL!="sd*|sr*", ATTR{removable}=="1", GOTO="persistent_storage_end"
 
 # probe filesystem metadata of optical drives which have a media inserted
-KERNEL=="sr*", ENV{ID_CDROM_MEDIA}=="?*", IMPORT{program}="/sbin/blkid -o udev -p -u noraid -O $env{ID_CDROM_MEDIA_SESSION_LAST_OFFSET} $tempnode"
+KERNEL=="sr*", ENV{ID_CDROM_MEDIA}=="?*", ENV{ID_CDROM_MEDIA_SESSION_LAST_OFFSET}=="?*", IMPORT{program}="/sbin/blkid -o udev -p -u noraid -O $env{ID_CDROM_MEDIA_SESSION_LAST_OFFSET} $tempnode"
+# single-session CDs do not have ID_CDROM_MEDIA_SESSION_LAST_OFFSET
+KERNEL=="sr*", ENV{ID_CDROM_MEDIA}=="?*", IMPORT{program}="/sbin/blkid -o udev -p -u noraid $tempnode"
 
 # probe filesystem metadata of disks
 KERNEL!="sr*", IMPORT{program}="/sbin/blkid -o udev -p $tempnode"