diff --git a/findunusedbd.sh b/findunusedbd.sh
index ea47c35..952bab2 100755
--- a/findunusedbd.sh
+++ b/findunusedbd.sh
@@ -15,25 +15,28 @@ get_metaset() {
 		if apt-cache show --no-all-versions "${name}=${ver}" \
 			| grep-dctrl -P "" -s Tag -n \
 			| sed 's/, /\n/g; s/[, ]//g;' \
-			| egrep '^(role::metapackage|role::dummy)$'; then
+			| egrep '^(role::metapackage|role::dummy)$' \
+			> /dev/null; then
 			ismeta="yes"
 		fi
 	fi
 	# check if there is any regular file in the package besides /usr/share/doc
 	if [ $ismeta = "no" ]; then
 		apt-get download "${name}=${ver}" > /dev/null
-		mkdir "$name"
+		# strip off architecture qualifier
+		pkgname=`echo $name | cut -d ':' -f 1`
+		mkdir "$pkgname"
 		# we cannot include the version here because apt urlencodes the : character
-		dpkg --extract ${name}_*.deb $name
-		if [ -d ${name}/usr/share/doc ]; then
-			rm -r ${name}/usr/share/doc
+		dpkg --extract ${pkgname}_*.deb $pkgname
+		if [ -d ${pkgname}/usr/share/doc ]; then
+			rm -r ${pkgname}/usr/share/doc
 		fi
 		# check if besides /usr/share/doc there is any regular file
 		# in this package (symlinks do not count)
-		if [ `find $name -type f | wc -l` -eq 0 ]; then
+		if [ `find $pkgname -type f | wc -l` -eq 0 ]; then
 			ismeta="yes"
 		fi
-		rm -r ${name}_${ver}_*.deb $name
+		rm -r ${pkgname}_*.deb $pkgname
 	fi
 	if [ $ismeta = "yes" ]; then
 		# retrieve all its unversioned dependencies
@@ -93,9 +96,12 @@ elif [ "$#" -eq 2 ]; then
 			# output the files belonging to all packages
 			dpkg --list | awk '$1 == "ii" { print $2, $3 }' | while read namever; do
 				set -- $namever
-				# strip off architecture qualifier
-				name=`echo $1 | cut -d ':' -f 1`
+				name=$1
 				ver=$2
+				# skip all sbuild dummy packages
+				case $name in
+					sbuild-build-depends*) continue;;
+				esac
 				if grep --line-regexp "${name}=${ver}" "${tmpdir}/bdselection.list"; then
 					# if the package contains no other files than in /usr/share/doc
 					# or if all the other files are symlinks