diff --git a/groupmerge.sh b/groupmerge.sh
index 5c1cfde..371be34 100755
--- a/groupmerge.sh
+++ b/groupmerge.sh
@@ -10,7 +10,9 @@ if [[ ! -e $1 || ! -e $2 ]]; then
 	echo "Use groupfile1 as the basis and merges missing entries from groupfile2"
 fi
 
-cat $1
+cat $1 | grep -v ":1000:"  
+# yes, group assignments of the host user will remain, but it won't hurt
+
 echo "# merged entries:"
 cat $2 | while read grp; do
  	name=$(echo $grp | cut -d ':' -f 1)
@@ -20,6 +22,10 @@ cat $2 | while read grp; do
 
 	line=$(cat $1 | grep -E "^$name:")
 	if [[ $line == "" ]]; then
-	  echo $name:$pass:$(($dgid + 2000)):$rest
+	  ngid=$(($dgid + 2000))
+	  echo $name:$pass:$ngid:$rest
+		if [[ -e /.dockerenv ]]; then
+			find / -group $dgid -mount -exec chgrp ngid {} \;
+		fi
 	fi
 done