diff --git a/scripts/pkgs-update-hook/update.secondary b/scripts/pkgs-update-hook/update.secondary
index c2feb59..3e7ccd4 100644
--- a/scripts/pkgs-update-hook/update.secondary
+++ b/scripts/pkgs-update-hook/update.secondary
@@ -4,11 +4,13 @@
 MAX_SIZE=20000
 
 bad_file_found=0
+new_rev=$3
+old_rev=$2
 tmp=$(mktemp /tmp/git.update.XXXXXX)
 tree=$(mktemp /tmp/git.diff-tree.XXXXXX)
 zero="0000000000000000000000000000000000000000"
 
-git diff-tree -r "$2" "$3" > $tree
+git diff-tree -r "$old_rev" "$new_rev" > $tree
 while read old_mode new_mode old_sha1 new_sha1 status name; do
     # skip lines showing parent commit
     [[ -z "$new_sha1" ]] && continue;