diff --git a/test/lisp/net/tramp-tests.el b/test/lisp/net/tramp-tests.el
index 9930a2c9e1..69dadcd107 100644
--- a/test/lisp/net/tramp-tests.el
+++ b/test/lisp/net/tramp-tests.el
@@ -5288,6 +5288,14 @@ tramp--test-check-files
 		  (setenv "PS1")
 		  (with-temp-buffer
 		    (should (zerop (process-file "env" nil t nil)))
+                    (tramp--test-message
+                     "coding-sytem: `%s' `%s'"
+                     coding-system-for-read coding-system-for-write )
+                    (tramp--test-message "search: `%s'" (getenv envvar))
+                    (let ((coding-system-for-read 'no-conversion)
+                          (coding-system-for-write 'no-conversion))
+                      (tramp--test-message "search: `%s'" (getenv envvar))
+                      (tramp--test-message "buffer: `%s'" (buffer-string)))
 		    (goto-char (point-min))
 		    (should
 		     (re-search-forward