Sed error on mac

bb.sh

@@ -785,8 +785,8 @@ tags_in_post() {
 # Prints one line with space-separated tags to stdout
 posts_with_tags() {
     [ $# -lt 1 ] && return
-    tag_files="$(echo "$@" | sed "s/\S\+/$prefix_tags&.html/g")"
     set -x
+    tag_files="$(for i in $@; do echo -n $prefix_tags""$i.html" "; done)"
     sed -n '/^<h3><a class="ablack" href="[^"]*">/{s/.*href="\([^"]*\)">.*/\1/;p;}' $tag_files
     set +x
 }