diff --git a/mozilla/netwerk/base/public/nsINetUtil.idl b/mozilla/netwerk/base/public/nsINetUtil.idl
index 8e41c692b59..26cda864569 100644
--- a/mozilla/netwerk/base/public/nsINetUtil.idl
+++ b/mozilla/netwerk/base/public/nsINetUtil.idl
@@ -161,7 +161,7 @@ interface nsINetUtil : nsISupports
 
   /** 
    * Skip graphic octets (0x20-0x7E) when escaping
-   * Skips all ascii octets when unescaping 
+   * Skips all ASCII octets (0x00-0x7F) when unescaping 
    */
   const unsigned long ESCAPE_URL_ONLY_NONASCII = 1 << 12;
 
diff --git a/mozilla/netwerk/test/unit/test_unescapestring.js b/mozilla/netwerk/test/unit/test_unescapestring.js
new file mode 100644
index 00000000000..7fb638e277c
--- /dev/null
+++ b/mozilla/netwerk/test/unit/test_unescapestring.js
@@ -0,0 +1,29 @@
+const ONLY_NONASCII = Components.interfaces.nsINetUtil.ESCAPE_URL_ONLY_NONASCII;
+const SKIP_CONTROL = Components.interfaces.nsINetUtil.ESCAPE_URL_SKIP_CONTROL;
+
+
+var tests = [
+  ["foo", "foo", 0],
+  ["foo%20bar", "foo bar", 0],
+  ["foo%2zbar", "foo%2zbar", 0],
+  ["foo%", "foo%", 0],
+  ["%zzfoo", "%zzfoo", 0],
+  ["foo%z", "foo%z", 0],
+  ["foo%00bar", "foo\x00bar", 0],
+  ["foo%ffbar", "foo\xffbar", 0],
+  ["%00%1b%20%61%7f%80%ff", "%00%1b%20%61%7f\x80\xff", ONLY_NONASCII],
+  ["%00%1b%20%61%7f%80%ff", "%00%1b a%7f\x80\xff", SKIP_CONTROL],
+  ["%00%1b%20%61%7f%80%ff", "%00%1b%20%61%7f\x80\xff", ONLY_NONASCII|SKIP_CONTROL]
+];
+
+function run_test() {
+  var util = Components.classes["@mozilla.org/network/util;1"]
+                       .getService(Components.interfaces.nsINetUtil);
+
+  for (var i = 0; i < tests.length; ++i) {
+    dump("Test " + i + " (" + tests[i][0] + ", " + tests[i][2] + ")\n");
+    do_check_eq(util.unescapeString(tests[i][0], tests[i][2]),
+                                    tests[i][1]);
+  }
+  dump(tests.length + " tests passed\n");
+}
diff --git a/mozilla/xpcom/io/nsEscape.h b/mozilla/xpcom/io/nsEscape.h
index dece84ed013..c57739db94d 100644
--- a/mozilla/xpcom/io/nsEscape.h
+++ b/mozilla/xpcom/io/nsEscape.h
@@ -122,7 +122,7 @@ enum EscapeMask {
   esc_OnlyASCII      = PR_BIT(11), /* causes non-ascii octets to be skipped */
   esc_OnlyNonASCII   = PR_BIT(12), /* causes _graphic_ ascii octets (0x20-0x7E) 
                                     * to be skipped when escaping. causes all
-                                    * ascii octets to be skipped when unescaping */
+                                    * ascii octets (<= 0x7F) to be skipped when unescaping */
   esc_AlwaysCopy     = PR_BIT(13), /* copy input to result buf even if escaping is unnecessary */
   esc_Colon          = PR_BIT(14), /* forces escape of colon */
   esc_SkipControl    = PR_BIT(15)  /* skips C0 and DEL from unescaping */