diff --git a/includes/common.inc b/includes/common.inc
index b6ea297..b4cb38f 100644
--- a/includes/common.inc
+++ b/includes/common.inc
@@ -608,7 +608,8 @@ function drupal_parse_url($url) {
 /**
  * Encodes a Drupal path for use in a URL.
  *
- * For aesthetic reasons slashes are not escaped.
+ * For aesthetic reasons slashes, commas and pluses are not escaped. Commas and
+ * pluses can be used as separators in taxonomy URLs.
  *
  * Note that url() takes care of calling this function, so a path passed to that
  * function should not be encoded in advance.
@@ -617,7 +618,10 @@ function drupal_parse_url($url) {
  *   The Drupal path to encode.
  */
 function drupal_encode_path($path) {
-  return str_replace('%2F', '/', rawurlencode($path));
+  return str_replace(
+      array('%2F', '%2C', '%2B'),
+      array('/', ',', '+'),
+      rawurlencode($path));
 }
 
 /**
diff --git a/modules/simpletest/tests/file.test b/modules/simpletest/tests/file.test
index dc12b1b..11a39a1 100644
--- a/modules/simpletest/tests/file.test
+++ b/modules/simpletest/tests/file.test
@@ -2259,10 +2259,13 @@ class FileDownloadTest extends FileTestCase {
     // Tilde (~) is excluded from this test because it is encoded by
     // rawurlencode() in PHP 5.2 but not in PHP 5.3, as per RFC 3986.
     // @see http://www.php.net/manual/en/function.rawurlencode.php#86506
-    $basename = " -._!$'\"()*@[]?&+%#,;=:\n\x00" . // "Special" ASCII characters.
+    // Comma (,) and plus (+) are used as AND and OR operators on taxonomy
+    // pages, they are left unencoded for aesthetic reason.
+    // @see http://drupal.org/node/113035
+    $basename = " -._+,!$'\"()*@[]?&%#;=:\n\x00" . // "Special" ASCII characters.
       "%23%25%26%2B%2F%3F" . // Characters that look like a percent-escaped string.
       "éøïвβ中國書۞"; // Characters from various non-ASCII alphabets.
-    $basename_encoded = '%20-._%21%24%27%22%28%29%2A%40%5B%5D%3F%26%2B%25%23%2C%3B%3D%3A__' .
+    $basename_encoded = '%20-._+,%21%24%27%22%28%29%2A%40%5B%5D%3F%26%25%23%3B%3D%3A__' .
       '%2523%2525%2526%252B%252F%253F' .
       '%C3%A9%C3%B8%C3%AF%D0%B2%CE%B2%E4%B8%AD%E5%9C%8B%E6%9B%B8%DB%9E';