diff --git a/lvmsnapshot.sh b/lvmsnapshot.sh
index 58d7d28..4d508fe 100755
--- a/lvmsnapshot.sh
+++ b/lvmsnapshot.sh
@@ -270,6 +270,7 @@ while getopts ':m:e:g:c:i:ndqh' OPTION ; do
 
         e)
             OPT_LVMEXTENSION=$OPTARG
+            ISSET_OPT_LVMEXTENSION="True"
             ;;
 
         c)
@@ -341,7 +342,7 @@ if [ ! -z $OPT_MAPPERINDEX ]; then
     MAPPERINDEX=$OPT_MAPPERINDEX
 fi
 
-if [ ! -z $OPT_LVMEXTENSION ]; then
+if [ ! -z $ISSET_OPT_LVMEXTENSION ]; then
     LVMEXTENSION=$OPT_LVMEXTENSION
 fi
 
@@ -541,4 +542,4 @@ else
     echo
     usage $EXIT_ERROR
 fi
-exit $EXIT_SUCCESS
\ No newline at end of file
+exit $EXIT_SUCCESS