diff --git a/guix/scripts/import/pypi.scm b/guix/scripts/import/pypi.scm
index a36065e5cf7584291e5f161e8f0fd3e19e4e0b29..1e03843840d3eb4171f040ff0350295926f09e0a 100644
--- a/guix/scripts/import/pypi.scm
+++ b/guix/scripts/import/pypi.scm
@@ -84,4 +84,8 @@ (define (parse-options)
          (unless sexp
            (leave (_ "failed to download meta-data for package '~a'~%")
                   package-name))
-         sexp)))))
+         sexp))
+      (()
+       (leave (_ "too few arguments~%")))
+      ((many ...)
+       (leave (_ "too many arguments~%"))))))