diff --git a/lisp/emacs-lisp/package-vc.el b/lisp/emacs-lisp/package-vc.el
index 8f0eedd2f8..eea5ad6c26 100644
--- a/lisp/emacs-lisp/package-vc.el
+++ b/lisp/emacs-lisp/package-vc.el
@@ -443,6 +443,12 @@ package-vc--unpack-1
            (auto-name (format "%s-autoloads.el" name))
            (extras (package-desc-extras pkg-desc))
            (lisp-dir (alist-get :lisp-dir extras)))
+      ;; Heuristic to guess a sub-directory with lisp files.
+      (when-let (((null lisp-dir))
+                 (dir (expand-file-name "lisp" pkg-dir))
+                 ((file-directory-p dir)))
+        (setq lisp-dir dir))
+
       (package-generate-autoloads
        name (file-name-concat pkg-dir lisp-dir))
       (when lisp-dir