diff --git a/qbase64-test.lisp b/qbase64-test.lisp
index 310fdf3..b92abb5 100644
--- a/qbase64-test.lisp
+++ b/qbase64-test.lisp
@@ -14,7 +14,7 @@
       (with-open-temporary-file (tmp :direction :output :element-type '(unsigned-byte 8))
         (write-sequence bytes tmp)
         (force-output tmp)
-        (let* ((encoded (uiop:run-program `("base64" "-b" ,(format nil "~A" linebreak) "-i" ,(namestring tmp)) :output (if (zerop linebreak) '(:string :stripped t) :string)))
+        (let* ((encoded (uiop:run-program `("base64" "-w" ,(format nil "~A" linebreak) ,(namestring tmp)) :output (if (zerop linebreak) '(:string :stripped t) :string) :error-output *error-output*))
                (length (length encoded)))
           (cond ((and (> length 1)
                       (string= (subseq encoded (- length 2))