diff --git a/lib/lexer.js b/lib/lexer.js
index 027d3e33..d9affe42 100644
--- a/lib/lexer.js
+++ b/lib/lexer.js
@@ -1,5 +1,5 @@
 (function() {
-  var ASSIGNED, CALLABLE, CODE, COFFEE_ALIASES, COFFEE_KEYWORDS, COMMENT, COMPARE, COMPOUND_ASSIGN, CONVERSIONS, HEREDOC, HEREDOC_INDENT, HEREGEX, HEREGEX_OMIT, IDENTIFIER, JSTOKEN, JS_FORBIDDEN, JS_KEYWORDS, LEADING_SPACES, LINE_BREAK, LOGIC, Lexer, MATH, MULTILINER, MULTI_DENT, NEXT_CHARACTER, NOT_REGEX, NO_NEWLINE, NUMBER, OPERATOR, REGEX, RESERVED, Rewriter, SHIFT, SIMPLESTR, TRAILING_SPACES, UNARY, WHITESPACE, _ref, compact, count, include, last, starts;
+  var ASSIGNED, CALLABLE, CODE, COFFEE_ALIASES, COFFEE_KEYWORDS, COMMENT, COMPARE, COMPOUND_ASSIGN, CONVERSIONS, HEREDOC, HEREDOC_INDENT, HEREGEX, HEREGEX_OMIT, IDENTIFIER, JSTOKEN, JS_FORBIDDEN, JS_KEYWORDS, LEADING_SPACES, LINE_BREAK, LOGIC, Lexer, MATH, MULTILINER, MULTI_DENT, NEGATABLE, NEXT_CHARACTER, NOT_REGEX, NO_NEWLINE, NUMBER, OPERATOR, REGEX, RESERVED, Rewriter, SHIFT, SIMPLESTR, TRAILING_SPACES, UNARY, WHITESPACE, _ref, compact, count, include, last, starts;
   Rewriter = require('./rewriter').Rewriter;
   _ref = require('./helpers'), include = _ref.include, count = _ref.count, starts = _ref.starts, compact = _ref.compact, last = _ref.last;
   exports.Lexer = (function() {
@@ -309,9 +309,9 @@
       return true;
     };
     Lexer.prototype.literalToken = function() {
-      var _ref2, match, prev, space, spaced, tag, val, value;
-      if (match = this.chunk.match(OPERATOR)) {
-        _ref2 = match, value = _ref2[0], space = _ref2[1];
+      var match, prev, ptag, pval, tag, value;
+      if (match = OPERATOR.exec(this.chunk)) {
+        value = match[0];
         if (CODE.test(value)) {
           this.tagParameters();
         }
@@ -319,19 +319,19 @@
         value = this.chunk.charAt(0);
       }
       this.i += value.length;
-      prev = last(this.tokens);
-      spaced = ((prev != null) ? prev.spaced : undefined);
       tag = value;
       if (value === '=') {
-        if (include(JS_FORBIDDEN, val = this.value())) {
+        if (include(JS_FORBIDDEN, pval = this.value())) {
           this.assignmentError();
         }
-        if (('or' === val || 'and' === val)) {
-          this.tokens.splice(-1, 1, ['COMPOUND_ASSIGN', CONVERSIONS[val] + '=', prev[2]]);
+        if (('or' === pval || 'and' === pval)) {
+          prev = last(this.tokens);
+          prev[0] = 'COMPOUND_ASSIGN';
+          prev[1] = CONVERSIONS[pval] + '=';
           return true;
         }
       }
-      if (value === ';') {
+      if (';' === value) {
         tag = 'TERMINATOR';
       } else if (include(LOGIC, value)) {
         tag = 'LOGIC';
@@ -345,20 +345,20 @@
         tag = 'UNARY';
       } else if (include(SHIFT, value)) {
         tag = 'SHIFT';
-      } else if (include(CALLABLE, this.tag()) && !spaced) {
+      } else if ((prev = last(this.tokens)) && !prev.spaced && include(CALLABLE, ptag = prev[0])) {
         if (value === '(') {
-          if (prev[0] === '?') {
+          if (ptag === '?') {
             prev[0] = 'FUNC_EXIST';
           }
           tag = 'CALL_START';
         } else if (value === '[') {
           tag = 'INDEX_START';
-          switch (this.tag()) {
+          switch (ptag) {
             case '?':
-              this.tag(0, 'INDEX_SOAK');
+              prev[0] = 'INDEX_SOAK';
               break;
             case '::':
-              this.tag(0, 'INDEX_PROTO');
+              prev[0] = 'INDEX_PROTO';
               break;
           }
         }
@@ -547,19 +547,13 @@
     Lexer.prototype.token = function(tag, value) {
       return this.tokens.push([tag, value, this.line]);
     };
-    Lexer.prototype.tag = function(index, newTag) {
+    Lexer.prototype.tag = function(index, tag) {
       var tok;
-      if (!(tok = last(this.tokens, index))) {
-        return null;
-      }
-      return (tok[0] = (newTag != null) ? newTag : tok[0]);
+      return (tok = last(this.tokens, index)) && ((tag != null) ? (tok[0] = tag) : tok[0]);
     };
     Lexer.prototype.value = function(index, val) {
       var tok;
-      if (!(tok = last(this.tokens, index))) {
-        return null;
-      }
-      return (tok[1] = (val != null) ? val : tok[1]);
+      return (tok = last(this.tokens, index)) && ((val != null) ? (tok[1] = val) : tok[1]);
     };
     Lexer.prototype.unfinished = function() {
       var prev, value;
@@ -585,7 +579,7 @@
   IDENTIFIER = /^[a-zA-Z_$][\w$]*/;
   NUMBER = /^0x[\da-f]+|^(?:\d+(\.\d+)?|\.\d+)(?:e[+-]?\d+)?/i;
   HEREDOC = /^("""|''')([\s\S]*?)(?:\n[ \t]*)?\1/;
-  OPERATOR = /^(?:-[-=>]?|\+[+=]?|[*&|\/%=<>^:!?]+)(?=([ \t]*))/;
+  OPERATOR = /^(?:-[-=>]?|\+[+=]?|[*&|\/%=<>^:!?]+)/;
   WHITESPACE = /^[ \t]+/;
   COMMENT = /^###([^#][\s\S]*?)(?:###[ \t]*\n|(?:###)?$)|^(?:\s*#(?!##[^#]).*)+/;
   CODE = /^[-=]>/;
@@ -610,6 +604,7 @@
   MATH = ['*', '/', '%'];
   NOT_REGEX = ['NUMBER', 'REGEX', '++', '--', 'FALSE', 'NULL', 'TRUE', ']'];
   CALLABLE = ['IDENTIFIER', 'SUPER', ')', ']', '}', 'STRING', '@', 'THIS', '?', '::'];
+  NEGATABLE = ['IN', 'OF', 'INSTANCEOF'];
   LINE_BREAK = ['INDENT', 'OUTDENT', 'TERMINATOR'];
   CONVERSIONS = {
     'and': '&&',
diff --git a/src/lexer.coffee b/src/lexer.coffee
index ae2590ca..785f1fcf 100644
--- a/src/lexer.coffee
+++ b/src/lexer.coffee
@@ -292,36 +292,37 @@ exports.Lexer = class Lexer
   # here. `;` and newlines are both treated as a `TERMINATOR`, we distinguish
   # parentheses that indicate a method call from regular parentheses, and so on.
   literalToken: ->
-    if match = @chunk.match OPERATOR
-      [value, space] = match
+    if match = OPERATOR.exec @chunk
+      [value] = match
       @tagParameters() if CODE.test value
     else
       value = @chunk.charAt 0
     @i += value.length
-    prev = last @tokens
-    spaced = prev?.spaced
     tag = value
     if value is '='
-      @assignmentError() if include JS_FORBIDDEN, val = @value()
-      if val in ['or', 'and']
-        @tokens.splice(-1, 1, ['COMPOUND_ASSIGN', CONVERSIONS[val] + '=', prev[2]])
+      @assignmentError() if include JS_FORBIDDEN, pval = @value()
+      if pval in ['or', 'and']
+        prev = last @tokens
+        prev[0] = 'COMPOUND_ASSIGN'
+        prev[1] = CONVERSIONS[pval] + '='
         return true
-    if value is ';'                         then tag = 'TERMINATOR'
-    else if include(LOGIC, value)           then tag = 'LOGIC'
-    else if include(MATH, value)            then tag = 'MATH'
-    else if include(COMPARE, value)         then tag = 'COMPARE'
-    else if include(COMPOUND_ASSIGN, value) then tag = 'COMPOUND_ASSIGN'
-    else if include(UNARY, value)           then tag = 'UNARY'
-    else if include(SHIFT, value)           then tag = 'SHIFT'
-    else if include(CALLABLE, @tag()) and not spaced
+    if ';' is                        value then tag = 'TERMINATOR'
+    else if include LOGIC          , value then tag = 'LOGIC'
+    else if include MATH           , value then tag = 'MATH'
+    else if include COMPARE        , value then tag = 'COMPARE'
+    else if include COMPOUND_ASSIGN, value then tag = 'COMPOUND_ASSIGN'
+    else if include UNARY          , value then tag = 'UNARY'
+    else if include SHIFT          , value then tag = 'SHIFT'
+    else if (prev = last @tokens) and not prev.spaced and
+         include(CALLABLE, ptag = prev[0])
       if value is '('
-        prev[0] = 'FUNC_EXIST' if prev[0] is '?'
+        prev[0] = 'FUNC_EXIST' if ptag is '?'
         tag = 'CALL_START'
       else if value is '['
         tag = 'INDEX_START'
-        switch @tag()
-          when '?'  then @tag 0, 'INDEX_SOAK'
-          when '::' then @tag 0, 'INDEX_PROTO'
+        switch ptag
+          when '?'  then prev[0] = 'INDEX_SOAK'
+          when '::' then prev[0] = 'INDEX_PROTO'
     @token tag, value
     true
 
@@ -468,15 +469,11 @@ exports.Lexer = class Lexer
   token: (tag, value) ->
     @tokens.push [tag, value, @line]
 
-  # Peek at a tag in the current token stream.
-  tag: (index, newTag) ->
-    return unless tok = last @tokens, index
-    tok[0] = newTag ? tok[0]
-
-  # Peek at a value in the current token stream.
+  # Peek at a tag/value in the current token stream.
+  tag  : (index, tag) ->
+    (tok = last @tokens, index) and if tag? then tok[0] = tag else tok[0]
   value: (index, val) ->
-    return unless tok = last @tokens, index
-    tok[1] = val ? tok[1]
+    (tok = last @tokens, index) and if val? then tok[1] = val else tok[1]
 
   # Are we in the midst of an unfinished expression?
   unfinished: ->
@@ -537,7 +534,7 @@ JS_FORBIDDEN = JS_KEYWORDS.concat RESERVED
 IDENTIFIER = /^[a-zA-Z_$][\w$]*/
 NUMBER     = /^0x[\da-f]+|^(?:\d+(\.\d+)?|\.\d+)(?:e[+-]?\d+)?/i
 HEREDOC    = /^("""|''')([\s\S]*?)(?:\n[ \t]*)?\1/
-OPERATOR   = /^(?:-[-=>]?|\+[+=]?|[*&|\/%=<>^:!?]+)(?=([ \t]*))/
+OPERATOR   = /// ^ (?: -[-=>]? | \+[+=]? | [*&|/%=<>^:!?]+ ) ///
 WHITESPACE = /^[ \t]+/
 COMMENT    = /^###([^#][\s\S]*?)(?:###[ \t]*\n|(?:###)?$)|^(?:\s*#(?!##[^#]).*)+/
 CODE       = /^[-=]>/