diff --git a/NEWS b/NEWS
index 6894779a..36f0566d 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,5 @@
+  - fall back to old uniqid()-behaviour when tempnam() fails in
+    core.write_file.php (messju)
   - fix capitalize modifier, don't rely on buggy ucwords (Monte)
   - make html_select_date work with negative timestamps, also
     force year range to include given date unless explicitly
diff --git a/libs/core/core.write_file.php b/libs/core/core.write_file.php
index f889f2a1..ea08adb8 100644
--- a/libs/core/core.write_file.php
+++ b/libs/core/core.write_file.php
@@ -25,11 +25,14 @@ function smarty_core_write_file($params, &$smarty)
 
     // write to tmp file, then rename it to avoid
     // file locking race condition
-    $_tmp_file = tempnam($_dirname, 'write_');
+    $_tmp_file = tempnam($_dirname, 'wrt');
 
-    if (!($fd = @fopen($_tmp_file, 'w'))) {
-        $smarty->trigger_error("problem writing temporary file '$_tmp_file'");
-        return false;
+    if (!($fd = @fopen($_tmp_file, 'wb'))) {
+        $_tmp_file = $_dirname . DIRECTORY_SEPARATOR . uniqid('wrt');
+        if (!($fd = @fopen($_tmp_file, 'wb'))) {
+            $smarty->trigger_error("problem writing temporary file '$_tmp_file'");
+            return false;
+        }
     }
 
     fwrite($fd, $params['contents']);