2 files changed, 7 insertions, 3 deletions

diff --git a/test/ChangeLog b/test/ChangeLog
index aded5473304..458d4df1f39 100644
--- a/test/ChangeLog
+++ b/test/ChangeLog
@@ -1,3 +1,8 @@
+2013-07-08  Kenichi Handa  <handa@gnu.org>
+
+        * automated/decoder-tests.el (decoder-tests-prefer-utf-8-read):
+        Use with-ccoding-priority to avoid side-effect (Bug#14781).
+
 2013-07-05  Michael Albinus  <michael.albinus@gmx.de>
 
         * automated/file-notify-tests.el
diff --git a/test/automated/decoder-tests.el b/test/automated/decoder-tests.el
index e1b05faf3c0..2e99fd7f115 100644
--- a/test/automated/decoder-tests.el
+++ b/test/automated/decoder-tests.el
@@ -213,10 +213,9 @@
 ;; PREFER is non-nil, prefer that coding system before reading.
 
 (defun decoder-tests-prefer-utf-8-read (file detect prefer)
-  (if prefer
-      (prefer-coding-system prefer))
   (with-temp-buffer
-    (insert-file-contents file)
+    (with-coding-priority (if prefer (list prefer))
+      (insert-file-contents file))
     (if (eq buffer-file-coding-system detect)
         nil
       (format "Invalid detection: %s" buffer-file-coding-system))))