diff --git a/esprima/character.py b/esprima/character.py
index 929706c..1e541d0 100644
--- a/esprima/character.py
+++ b/esprima/character.py
@@ -71,18 +71,15 @@
 ))
 LINE_TERMINATOR = set(('\x0A', '\x0D', '\u2028', '\u2029'))
 
-DECIMAL_CONV = dict((c, n) for n, c in enumerate('0123456789'))
-OCTAL_CONV = dict((c, n) for n, c in enumerate('01234567'))
 HEX_CONV = dict((c, n) for n, c in enumerate('0123456789abcdef'))
 for n, c in enumerate('ABCDEF', 10):
     HEX_CONV[c] = n
-DECIMAL_DIGIT = set(DECIMAL_CONV.keys())
-OCTAL_DIGIT = set(OCTAL_CONV.keys())
+OCTAL_DIGIT = set('01234567')
+DECIMAL_DIGIT = OCTAL_DIGIT | {"8", "9"}
 HEX_DIGIT = set(HEX_CONV.keys())
 
 del U_CATEGORIES, UNICODE_LETTER, UNICODE_COMBINING_MARK
 del UNICODE_DIGIT, UNICODE_CONNECTOR_PUNCTUATION
-del DECIMAL_CONV, OCTAL_CONV, HEX_CONV
 
 class Character:
     @staticmethod
diff --git a/esprima/parser.py b/esprima/parser.py
index 2639f4c..7478af0 100644
--- a/esprima/parser.py
+++ b/esprima/parser.py
@@ -592,7 +592,7 @@ def parsePrimaryExpression(self):
                 self.scanner.index = self.startMarker.index
                 token = self.nextRegexToken()
                 raw = self.getTokenRaw(token)
-                expr = self.finalize(node, Node.RegexLiteral(token.regex, raw, token.pattern, token.flags))
+                expr = self.finalize(node, Node.RegexLiteral("/" + token.pattern + "/" + token.flags, raw, token.pattern, token.flags))
             else:
                 expr = self.throwUnexpectedToken(self.nextToken())
 
diff --git a/esprima/scanner.py b/esprima/scanner.py
index 53502a5..e15f553 100644
--- a/esprima/scanner.py
+++ b/esprima/scanner.py
@@ -27,17 +27,20 @@
 
 from .objects import Object
 from .compat import xrange, unicode, uchr, uord
-from .character import Character, HEX_CONV, OCTAL_CONV
+from .character import Character, HEX_CONV
 from .messages import Messages
 from .token import Token
 
 
-def hexValue(ch):
+def hexDigitValue(ch):
     return HEX_CONV[ch]
 
 
-def octalValue(ch):
-    return OCTAL_CONV[ch]
+_zeroDigitCode = ord("0")
+
+
+def octalDigitValue(ch):
+    return ord(ch) - _zeroDigitCode
 
 
 class RegExp(Object):
@@ -382,7 +385,7 @@ def scanHexEscape(self, prefix):
             if not self.eof() and Character.isHexDigit(self.source[self.index]):
                 ch = self.source[self.index]
                 self.index += 1
-                code = code * 16 + hexValue(ch)
+                code = code * 16 + hexDigitValue(ch)
             else:
                 return None
 
@@ -402,7 +405,7 @@ def scanUnicodeCodePointEscape(self):
             if not Character.isHexDigit(ch):
                 break
 
-            code = code * 16 + hexValue(ch)
+            code = code * 16 + hexDigitValue(ch)
 
         if code > 0x10FFFF or ch != '}':
             self.throwUnexpectedToken()
@@ -484,17 +487,17 @@ def getComplexIdentifier(self):
     def octalToDecimal(self, ch):
         # \0 is not octal escape sequence
         octal = ch != '0'
-        code = octalValue(ch)
+        code = octalDigitValue(ch)
 
         if not self.eof() and Character.isOctalDigit(self.source[self.index]):
             octal = True
-            code = code * 8 + octalValue(self.source[self.index])
+            code = code * 8 + octalDigitValue(self.source[self.index])
             self.index += 1
 
             # 3 digits are only allowed when string starts
             # with 0, 1, 2, 3
             if ch in '0123' and not self.eof() and Character.isOctalDigit(self.source[self.index]):
-                code = code * 8 + octalValue(self.source[self.index])
+                code = code * 8 + octalDigitValue(self.source[self.index])
                 self.index += 1
 
         return Octal(octal, code)