--- a/js/src/vm/Unicode.cpp
+++ b/js/src/vm/Unicode.cpp
@@ -191,17 +191,17 @@ const CharacterInfo js_charinfo[] = {
     {0, 54756, 2},
     {0, 54787, 2},
     {0, 54753, 2},
     {0, 54754, 2},
     {0, 54721, 2},
     {58272, 0, 2},
 };
 
-const uint16_t index1[] = {
+const uint8_t index1[] = {
       0,   1,   2,   3,   4,   5,   6,   7,   8,   9,  10,  11,  12,  13,  14,  15,  16,  17,
      18,  19,  20,  21,  22,  23,  24,  25,  26,  27,  28,  29,  30,  31,  32,  33,  34,  34,
      35,  36,  37,  38,  39,  40,  41,  42,  43,  44,  45,  46,  47,  48,  49,  50,  51,  52,
      53,  54,  55,  56,  57,  58,  59,  60,  61,  62,  63,  64,  65,  66,  26,  26,  26,  26,
      26,  67,  68,  69,  70,  71,  72,  73,  74,  26,  26,  26,  26,  26,  26,  26,  26,  75,
      76,  77,  78,  79,  80,  81,  82,  83,  84,  85,  86,  87,  88,  89,  90,  91,  92,  34,
      93,  94,  95,  96,  97,  98,  34,  99,  26, 100,  26, 101, 102, 102, 103, 102, 104, 105,
     106, 107, 108, 109, 110, 111, 112, 113, 114,  34,  34,  34,  34,  34,  34,  34,  34,  34,
@@ -251,17 +251,17 @@ const uint16_t index1[] = {
      34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,
      34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,
      34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,
      34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,  34,
      34,  34,  34,  34,  34,  34,  26,  26,  26,  26, 158, 158,  26, 159, 160, 161, 162, 163,
      26,  26,  26,  26, 164, 165, 166, 167, 168, 169,  26, 170, 171, 172, 173, 174,
 };
 
-const uint16_t index2[] = {
+const uint8_t index2[] = {
       0,   0,   0,   0,   0,   0,   0,   0,   0,   1,   1,   1,   1,   1,   0,   0,   0,   0,
       0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   1,   0,   0,   0,
       0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   2,   2,   2,   2,   2,   2,
       2,   2,   2,   2,   0,   0,   0,   0,   0,   0,   0,   3,   3,   3,   3,   3,   3,   3,
       3,   3,   3,   3,   3,   3,   3,   3,   3,   3,   3,   3,   3,   3,   3,   3,   3,   3,
       3,   0,   0,   0,   0,   2,   0,   4,   4,   4,   4,   4,   4,   4,   4,   4,   4,   4,
       4,   4,   4,   4,   4,   4,   4,   4,   4,   4,   4,   4,   4,   4,   4,   0,   0,   0,
       0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,

--- a/js/src/vm/Unicode.h
+++ b/js/src/vm/Unicode.h
@@ -155,24 +155,24 @@ class CharacterInfo {
         return flags & CharFlag::ENCLOSING_MARK;
     }
 
     inline bool isCombiningSpacingMark() const {
         return flags & CharFlag::COMBINING_SPACING_MARK;
     }
 };
 
-extern const uint16_t index1[];
-extern const uint16_t index2[];
+extern const uint8_t index1[];
+extern const uint8_t index2[];
 extern const CharacterInfo js_charinfo[];
 
 inline const CharacterInfo&
 CharInfo(jschar code)
 {
-    uint16_t index = index1[code >> 6];
+    size_t index = index1[code >> 6];
     index = index2[(index << 6) + (code & 0x3f)];
 
     return js_charinfo[index];
 }
 
 inline bool
 IsIdentifierStart(jschar ch)
 {

--- a/js/src/vm/make_unicode.py
+++ b/js/src/vm/make_unicode.py
@@ -262,23 +262,23 @@ if (typeof reportCompare === "function")
     for d in table:
         data_file.write('    {')
         data_file.write(', '.join((str(e) for e in d)))
         data_file.write('},\n')
     data_file.write('};\n')
     data_file.write('\n')
 
     def dump(data, name, file):
-        file.write('const uint16_t ' + name + '[] = {\n')
+        file.write('const uint8_t ' + name + '[] = {\n')
 
         line = pad = ' ' * 4
         lines = []
         for entry in data:
+            assert entry < 256
             s = str(entry)
-            assert len(s) <= 3
             s = s.rjust(3)
 
             if len(line + s) + 5 > 99:
                 lines.append(line.rstrip())
                 line = pad + s + ', '
             else:
                 line = line + s + ', '
         lines.append(line.rstrip())