--- a/testing/mochitest/tests/SimpleTest/NativeKeyCodes.js
+++ b/testing/mochitest/tests/SimpleTest/NativeKeyCodes.js
@@ -5,16 +5,23 @@
  */
 
 // Windows
 // Windows' native key code values may include scan code value which can be
 // retrieved with |((code & 0xFFFF0000 >> 16)|.  If the value is 0, it will
 // be computed with active keyboard layout automatically.
 // FYI: Don't define scan code here for printable keys, numeric keys and
 //      IME keys because they depend on active keyboard layout.
+// XXX: Although, ABNT C1 key depends on keyboard layout in strictly speaking.
+//      However, computing its scan code from the virtual keycode,
+//      WIN_VK_ABNT_C1, doesn't work fine (computed as 0x0073, "IntlRo").
+//      Therefore, we should specify it here explicitly (it should be 0x0056,
+//      "IntlBackslash").  Fortunately, the key always generates 0x0056 with
+//      any keyboard layouts as far as I've tested.  So, this must be safe to
+//      test new regressions.
 
 const WIN_VK_LBUTTON                    = 0x00000001;
 const WIN_VK_RBUTTON                    = 0x00000002;
 const WIN_VK_CANCEL                     = 0xE0460003;
 const WIN_VK_MBUTTON                    = 0x00000004;
 const WIN_VK_XBUTTON1                   = 0x00000005;
 const WIN_VK_XBUTTON2                   = 0x00000006;
 const WIN_VK_BACK                       = 0x000E0008;
@@ -172,17 +179,17 @@ const WIN_VK_LAUNCH_APP1                
 const WIN_VK_LAUNCH_APP2                = 0xE02100B7;
 const WIN_VK_OEM_1                      = 0x000000BA;
 const WIN_VK_OEM_PLUS                   = 0x000000BB;
 const WIN_VK_OEM_COMMA                  = 0x000000BC;
 const WIN_VK_OEM_MINUS                  = 0x000000BD;
 const WIN_VK_OEM_PERIOD                 = 0x000000BE;
 const WIN_VK_OEM_2                      = 0x000000BF;
 const WIN_VK_OEM_3                      = 0x000000C0;
-const WIN_VK_ABNT_C1                    = 0x000000C1;
+const WIN_VK_ABNT_C1                    = 0x005600C1;
 const WIN_VK_ABNT_C2                    = 0x000000C2;
 const WIN_VK_OEM_4                      = 0x000000DB;
 const WIN_VK_OEM_5                      = 0x000000DC;
 const WIN_VK_OEM_6                      = 0x000000DD;
 const WIN_VK_OEM_7                      = 0x000000DE;
 const WIN_VK_OEM_8                      = 0x000000DF;
 const WIN_VK_OEM_NEC_DP1                = 0x000000E0;
 const WIN_VK_OEM_AX                     = 0x000000E1;

--- a/widget/tests/test_keycodes.xul
+++ b/widget/tests/test_keycodes.xul
@@ -2842,20 +2842,20 @@ function* runKeyEventTests()
                   "|", "Backquote", nsIDOMKeyEvent.DOM_VK_PIPE, "|", SHOULD_DELIVER_ALL, KeyboardEvent.DOM_KEY_LOCATION_STANDARD);
     yield testKey({layout:KEYBOARD_LAYOUT_NORWEGIAN, keyCode:WIN_VK_OEM_5,
                    modifiers:{shiftKey:1}, chars:"\u00A7"},
                   "\u00A7", "Backquote", nsIDOMKeyEvent.DOM_VK_PIPE, "\u00A7", SHOULD_DELIVER_ALL, KeyboardEvent.DOM_KEY_LOCATION_STANDARD);
 
     // Brazilian ABNT
     yield testKey({layout:KEYBOARD_LAYOUT_BRAZILIAN_ABNT, keyCode:WIN_VK_ABNT_C1,
                    modifiers:{}, chars:"/"},
-                  "/", "IntlRo" /* TODO, should be "IntlBackslash" */, nsIDOMKeyEvent.DOM_VK_SLASH, "/", SHOULD_DELIVER_ALL, KeyboardEvent.DOM_KEY_LOCATION_STANDARD);
+                  "/", "IntlBackslash", nsIDOMKeyEvent.DOM_VK_SLASH, "/", SHOULD_DELIVER_ALL, KeyboardEvent.DOM_KEY_LOCATION_STANDARD);
     yield testKey({layout:KEYBOARD_LAYOUT_BRAZILIAN_ABNT, keyCode:WIN_VK_ABNT_C1,
                    modifiers:{shiftKey:1}, chars:"?"},
-                  "?", "IntlRo" /* TODO, should be "IntlBackslash" */, nsIDOMKeyEvent.DOM_VK_SLASH, "?", SHOULD_DELIVER_ALL, KeyboardEvent.DOM_KEY_LOCATION_STANDARD);
+                  "?", "IntlBackslash", nsIDOMKeyEvent.DOM_VK_SLASH, "?", SHOULD_DELIVER_ALL, KeyboardEvent.DOM_KEY_LOCATION_STANDARD);
     yield testKey({layout:KEYBOARD_LAYOUT_BRAZILIAN_ABNT, keyCode:WIN_VK_ABNT_C2,
                    modifiers:{numLockKey:1}, chars:"."},
                   ".", "NumpadComma", nsIDOMKeyEvent.DOM_VK_SEPARATOR, ".", SHOULD_DELIVER_ALL, KeyboardEvent.DOM_KEY_LOCATION_NUMPAD);
     yield testKey({layout:KEYBOARD_LAYOUT_BRAZILIAN_ABNT, keyCode:WIN_VK_DECIMAL,
                    modifiers:{numLockKey:1}, chars:","},
                   ",", "NumpadDecimal", nsIDOMKeyEvent.DOM_VK_DECIMAL, ",", SHOULD_DELIVER_ALL, KeyboardEvent.DOM_KEY_LOCATION_NUMPAD);
 
     // Mac JIS keyboard