diff --git a/collects/meta/planet2-index/planet-compat/main.rkt b/collects/meta/planet2-index/planet-compat/main.rkt
index b8669113dd..8c3d24f465 100644
--- a/collects/meta/planet2-index/planet-compat/main.rkt
+++ b/collects/meta/planet2-index/planet-compat/main.rkt
@@ -341,7 +341,7 @@
             (unless (file-exists? pkg-pth)
               (printf "Packaging ~a\n" pkg-short)
               (parameterize ([current-directory work])
-                (system (format "raco pkg create ~a" pkg-name))
+                (system (format "raco pkg create --format plt ~a" pkg-name))
                 (rename-file-or-directory
                  (build-path work pkg-name.plt)
                  pkg-pth)