diff --git a/ansi-tests/format-x.lsp b/ansi-tests/format-x.lsp
index 51d4f8adfa964029f0ed80162c8cabd74ef361eb..54e6137c2bb37c4ebf0f61c370540fd836c23405 100644
--- a/ansi-tests/format-x.lsp
+++ b/ansi-tests/format-x.lsp
@@ -319,7 +319,7 @@
    (loop for i from 0 to 10
 	 for args = (make-list i)
 	 for s = (apply #'format nil "~#x" #x1b3fe args)
-	 collect s))
+	 collect (string-upcase s)))
   "1B3FE"
   "1B3FE"
   "1B3FE"