diff --git a/src/zfs-auto-snapshot.sh b/src/zfs-auto-snapshot.sh
index cd88f0f..f223286 100644
--- a/src/zfs-auto-snapshot.sh
+++ b/src/zfs-auto-snapshot.sh
@@ -43,6 +43,7 @@ opt_pre_snapshot=''
 opt_post_snapshot=''
 opt_do_snapshots=1
 opt_min_size=0
+opt_changed=0
 
 # Global summary statistics.
 DESTRUCTION_COUNT='0'
@@ -57,6 +58,7 @@ print_usage ()
 {
 	echo "Usage: $0 [options] [-l label] <'//' | name [name...]>
   --default-exclude  Exclude datasets if com.sun:auto-snapshot is unset.
+  -c, --changed      Snap only if data written > 0.
   -d, --debug        Print debugging messages.
   -e, --event=EVENT  Set the com.sun:auto-snapshot-desc property to EVENT.
       --fast         Use a faster zfs list invocation.
@@ -164,9 +166,9 @@ do_snapshots () # properties, flags, snapname, oldglob, [targets...]
 	do
                 # Check if size check is > 0
                 size_check_skip=0
+                bytes_written=`zfs get -Hp -o value written $ii`
                 if [ "$opt_min_size" -gt 0 ]
                 then
-                        bytes_written=`zfs get -Hp -o value written $ii`
                         kb_written=$(( $bytes_written / 1024 ))
                         if [ "$kb_written" -lt "$opt_min_size" ]
                         then
@@ -176,7 +178,20 @@ do_snapshots () # properties, flags, snapname, oldglob, [targets...]
                                         echo "Skipping target $ii, only $kb_written kB written since last snap. opt_min_size is $opt_min_size"
                                 fi
                         fi
-                fi
+				fi
+				
+                # Force check if data changed
+                if [ "$opt_changed" -eq 1 ]
+                then
+				        if [ "$bytes_written" -eq 0 ]
+                        then
+                                size_check_skip=1
+                                if [ $opt_verbose -gt 0 ]
+                                then
+                                        echo "Skipping target $ii, 0 bytes written since last snap."
+                                fi
+                        fi
+				fi
 
                 if [ -n "$opt_do_snapshots" -a "$size_check_skip" -eq 0 ]
 		then
@@ -245,6 +260,10 @@ eval set -- "$GETOPT"
 while [ "$#" -gt '0' ]
 do
 	case "$1" in
+		(-c|--changed)
+			opt_changed=1
+			shift 1
+			;;
 		(-d|--debug)
 			opt_debug='1'
 			opt_quiet=''
@@ -629,3 +648,4 @@ print_log notice "@$SNAPNAME," \
 
 exit 0
 # }
+