diff --git a/auto-update b/auto-update
index 84849c7..d7e0a5b 100755
--- a/auto-update
+++ b/auto-update
@@ -27,19 +27,22 @@ latest() { : \
      &&  {  [ -d "$dir" ] && [ -f "$dir/$df" ] && [ -s "$dir/$df" ] \
          || { note "missing $df, skipping $dir ($tag)"; continue ;} \
          ;} \
-     && ours="$(grep -F "$tag"= "$dir/$df" | grep -Eo '[0-9a-f]{40}')" \
+     && grep -Fq "$tag=" "$dir/$df" \
+     && ours="$(grep -F "$tag=" "$dir/$df" | cut -d= -f2-)" \
      && theirs="$(latest "$url")" ours="${ours%%$n*}" theirs="${theirs%%$n*}" \
-     &&  if [ ${#ours} = 0 ] || [ ${#theirs} = 0 ] \
+     &&  if [ ${#theirs} = 0 ] \
         ;then note "failed to retrieve update for $dir ($tag)" \
         ;elif [ "$ours" != "$theirs" ] \
         ;then any=1 && note "updating $dir ($tag)" \
          && other="${tag%_COMMIT}_SHA256" && tgz="${url%/}" \
          && tgz="${tgz%%/tree/*}" && tgz="$tgz/archive/$theirs.tar.gz" \
          &&  {  sum="$(curl $flags "$tgz" | sha256sum - | awk '{print $1}')" \
-             && notwa-util/shed "$dir/$df" "s/$ours/$theirs/g" \
+             && notwa-util/shed "$dir/$df" "s/$tag=$ours/$tag=$theirs/g" \
              && notwa-util/shed "$dir/$df" "s/$other=.*/$other=$sum/g" \
              ;} \
          || note "failed to apply update for $dir ($tag)" \
-    ;fi ;done \
+        ;fi \
+     || note "failed to determine update for $dir ($tag)" \
+    ;done \
  && { [ $any = 1 ] || note "no new updates" ;} \
 ;