diff --git a/lib/lexer.js b/lib/lexer.js
index f1caca4d..f83f64ee 100644
--- a/lib/lexer.js
+++ b/lib/lexer.js
@@ -103,8 +103,8 @@
           if (!(string = this.balancedString(this.chunk, [['"', '"'], ['#{', '}']]))) {
             return false;
           }
-          if (~string.indexOf('#{')) {
-            this.interpolateString(string);
+          if (0 < string.indexOf('#{', 1)) {
+            this.interpolateString(string.slice(1, -1));
           } else {
             this.token('STRING', this.escapeLines(string));
           }
@@ -127,12 +127,12 @@
         quote: quote,
         indent: null
       });
-      if (quote === '"' && ~doc.indexOf('#{')) {
-        this.interpolateString(quote + doc + quote, {
+      if (quote === '"' && (0 <= doc.indexOf('#{'))) {
+        this.interpolateString(doc, {
           heredoc: true
         });
       } else {
-        this.token('STRING', quote + this.escapeLines(doc, true) + quote);
+        this.token('STRING', this.makeString(doc, quote, true));
       }
       this.line += count(heredoc, '\n');
       this.i += heredoc.length;
@@ -186,7 +186,7 @@
       var _i, _len, _ref2, _ref3, _this, body, flags, heregex, re, tag, tokens, value;
       _ref2 = match, heregex = _ref2[0], body = _ref2[1], flags = _ref2[2];
       this.i += heregex.length;
-      if (!(~body.indexOf('#{'))) {
+      if (0 > body.indexOf('#{')) {
         re = body.replace(HEREGEX_OMIT, '').replace(/\//g, '\\/');
         this.token('REGEX', "/" + (re || '(?:)') + "/" + flags);
         return true;
@@ -194,7 +194,7 @@
       this.token('IDENTIFIER', 'RegExp');
       this.tokens.push(['CALL_START', '(']);
       tokens = [];
-      _ref2 = this.interpolateString('"' + body + '"', {
+      _ref2 = this.interpolateString(body, {
         regex: true
       });
       for (_i = 0, _len = _ref2.length; _i < _len; _i++) {
@@ -202,10 +202,11 @@
         if (tag === 'TOKENS') {
           tokens.push.apply(tokens, value);
         } else {
-          if (!(value = value.slice(1, -1).replace(HEREGEX_OMIT, ''))) {
+          if (!(value = value.replace(HEREGEX_OMIT, ''))) {
             continue;
           }
-          tokens.push(['STRING', '"' + value.replace(/[\\\"]/g, '\\$&') + '"']);
+          value = value.replace(/\\/g, '\\\\');
+          tokens.push(['STRING', this.makeString(value, '"', true)]);
         }
         tokens.push(['+', '+']);
       }
@@ -385,13 +386,13 @@
       return accessor ? 'accessor' : false;
     };
     Lexer.prototype.sanitizeHeredoc = function(doc, options) {
-      var _ref2, attempt, herecomment, indent, match, quote;
+      var _ref2, attempt, herecomment, indent, match;
       _ref2 = options, indent = _ref2.indent, herecomment = _ref2.herecomment;
-      if (herecomment && !include(doc, '\n')) {
+      if (herecomment && 0 > doc.indexOf('\n')) {
         return doc;
       }
       if (!(herecomment)) {
-        while ((match = HEREDOC_INDENT.exec(doc))) {
+        while (match = HEREDOC_INDENT.exec(doc)) {
           attempt = match[1];
           if (indent === null || (0 < (_ref2 = attempt.length)) && (_ref2 < indent.length)) {
             indent = attempt;
@@ -401,17 +402,8 @@
       if (indent) {
         doc = doc.replace(RegExp("\\n" + indent, "g"), '\n');
       }
-      if (herecomment) {
-        return doc;
-      }
-      quote = options.quote;
-      doc = doc.replace(/^\n/, '');
-      doc = doc.replace(/\\([\s\S])/g, function(m, c) {
-        return ('\n' === c || quote === c) ? c : m;
-      });
-      doc = doc.replace(RegExp("" + quote, "g"), '\\$&');
-      if (quote === "'") {
-        doc = this.escapeLines(doc, true);
+      if (!(herecomment)) {
+        doc = doc.replace(/^\n/, '');
       }
       return doc;
     };
@@ -487,15 +479,11 @@
       return !i ? false : str.slice(0, i);
     };
     Lexer.prototype.interpolateString = function(str, options) {
-      var _i, _len, _ref2, _this, char, expr, heredoc, i, inner, interpolated, lexer, nested, pi, regex, tag, tok, tokens, value;
-      if (str.length < 5) {
-        return this.token('STRING', this.escapeLines(str, heredoc));
-      }
+      var _len, _ref2, _this, char, expr, heredoc, i, inner, interpolated, nested, pi, regex, tag, tokens, value;
       _ref2 = options || (options = {}), heredoc = _ref2.heredoc, regex = _ref2.regex;
-      lexer = new Lexer;
       tokens = [];
-      pi = 1;
-      i = 0;
+      pi = 0;
+      i = -1;
       while (char = str.charAt(i += 1)) {
         if (char === '\\') {
           i += 1;
@@ -505,45 +493,39 @@
           continue;
         }
         if (pi < i) {
-          tokens.push(['STRING', '"' + str.slice(pi, i) + '"']);
+          tokens.push(['TO_BE_STRING', str.slice(pi, i)]);
         }
         inner = expr.slice(1, -1).replace(LEADING_SPACES, '').replace(TRAILING_SPACES, '');
         if (inner.length) {
-          if (heredoc) {
-            inner = inner.replace(/\\\"/g, '"');
-          }
-          nested = lexer.tokenize("(" + inner + "\n)", {
-            line: this.line
+          nested = new Lexer().tokenize(inner, {
+            line: this.line,
+            rewrite: false
           });
-          for (_i = 0, _len = nested.length; _i < _len; _i++) {
-            tok = nested[_i];
-            if (tok[0] === 'CALL_END') {
-              (tok[0] = ')');
-            }
-          }
           nested.pop();
-          if (nested.length < 5) {
-            nested.pop();
-            nested.shift();
+          if (nested.length > 1) {
+            nested.unshift(['(', '(']);
+            nested.push([')', ')']);
           }
           tokens.push(['TOKENS', nested]);
         }
         i += expr.length;
         pi = i + 1;
       }
-      if ((i > pi) && (pi < str.length - 1)) {
-        tokens.push(['STRING', '"' + str.slice(pi)]);
+      if ((i > pi) && (pi < str.length)) {
+        tokens.push(['TO_BE_STRING', str.slice(pi)]);
       }
       if (regex) {
         return tokens;
       }
-      interpolated = tokens.length > 1;
-      if ((((_ref2 = tokens[0]) != null) ? _ref2[0] !== 'STRING' : undefined)) {
-        tokens.unshift(['STRING', '""']);
+      if (!(tokens.length)) {
+        return this.token('STRING', '""');
       }
-      if (interpolated) {
+      if (interpolated = tokens.length > 1) {
         this.token('(', '(');
       }
+      if (tokens[0][0] !== 'TO_BE_STRING') {
+        this.tokens.push(['STRING', '""'], ['+', '+']);
+      }
       for (i = 0, _len = tokens.length; i < _len; i++) {
         _ref2 = tokens[i], tag = _ref2[0], value = _ref2[1];
         if (i) {
@@ -552,7 +534,7 @@
         if (tag === 'TOKENS') {
           (_this = this.tokens).push.apply(_this, value);
         } else {
-          this.token(tag, this.escapeLines(value, heredoc));
+          this.token('STRING', this.makeString(value, '"', heredoc));
         }
       }
       if (interpolated) {
@@ -584,6 +566,13 @@
     Lexer.prototype.escapeLines = function(str, heredoc) {
       return str.replace(MULTILINER, heredoc ? '\\n' : '');
     };
+    Lexer.prototype.makeString = function(body, quote, heredoc) {
+      body = body.replace(/\\([\s\S])/g, function($amp, $1) {
+        return ('\n' === $1 || quote === $1) ? $1 : $amp;
+      });
+      body = body.replace(RegExp("" + quote, "g"), '\\$&');
+      return quote + this.escapeLines(body, heredoc) + quote;
+    };
     return Lexer;
   })();
   JS_KEYWORDS = ['if', 'else', 'true', 'false', 'new', 'return', 'try', 'catch', 'finally', 'throw', 'break', 'continue', 'for', 'in', 'while', 'delete', 'instanceof', 'typeof', 'switch', 'super', 'extends', 'class', 'this', 'null', 'debugger'];
@@ -593,7 +582,7 @@
   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/;
+  HEREDOC = /^("""|''')([\s\S]*?)(?:\n[ \t]*)?\1/;
   OPERATOR = /^(?:-[-=>]?|\+[+=]?|[*&|\/%=<>^:!?]+)(?=([ \t]*))/;
   WHITESPACE = /^[ \t]+/;
   COMMENT = /^###([^#][\s\S]*?)(?:###[ \t]*\n|(?:###)?$)|^(?:\s*#(?!##[^#]).*)+/;
diff --git a/lib/nodes.js b/lib/nodes.js
index 9edeecd4..bf8c78dd 100644
--- a/lib/nodes.js
+++ b/lib/nodes.js
@@ -220,10 +220,10 @@
       var code;
       code = this.compileNode(o);
       if (o.scope.hasAssignments(this)) {
-        code = ("" + this.tab + "var " + (o.scope.compiledAssignments()) + ";\n" + code);
+        code = ("" + (this.tab) + "var " + (o.scope.compiledAssignments()) + ";\n" + code);
       }
       if (!o.globals && o.scope.hasDeclarations(this)) {
-        code = ("" + this.tab + "var " + (o.scope.compiledDeclarations()) + ";\n" + code);
+        code = ("" + (this.tab) + "var " + (o.scope.compiledDeclarations()) + ";\n" + code);
       }
       return code;
     };
@@ -295,7 +295,7 @@
       if (this.expression.isStatement(o)) {
         o.asStatement = true;
       }
-      return "" + this.tab + "return " + (this.expression.compile(o)) + ";";
+      return "" + (this.tab) + "return " + (this.expression.compile(o)) + ";";
     };
     return ReturnNode;
   })();
@@ -588,7 +588,7 @@
       a = o.scope.freeVariable('ctor');
       b = o.scope.freeVariable('ref');
       c = o.scope.freeVariable('result');
-      return "(function() {\n" + (idt = this.idt(1)) + "var ctor = function() {};\n" + idt + (utility('extends')) + "(ctor, " + a + " = " + (this.variable.compile(o)) + ");\n" + idt + "return typeof (" + c + " = " + a + ".apply(" + b + " = new ctor, " + splatargs + ")) === \"object\" ? " + c + " : " + b + ";\n" + this.tab + "})." + call;
+      return "(function() {\n" + (idt = this.idt(1)) + "var ctor = function() {};\n" + idt + (utility('extends')) + "(ctor, " + a + " = " + (this.variable.compile(o)) + ");\n" + idt + "return typeof (" + c + " = " + a + ".apply(" + b + " = new ctor, " + splatargs + ")) === \"object\" ? " + c + " : " + b + ";\n" + (this.tab) + "})." + call;
     };
     return CallNode;
   })();
@@ -692,9 +692,9 @@
       }
       idx = del(o, 'index');
       step = del(o, 'step');
-      vars = ("" + idx + " = " + this.fromVar);
-      intro = ("(" + this.fromVar + " <= " + this.toVar + " ? " + idx);
-      compare = ("" + intro + " <" + this.equals + " " + this.toVar + " : " + idx + " >" + this.equals + " " + this.toVar + ")");
+      vars = ("" + idx + " = " + (this.fromVar));
+      intro = ("(" + (this.fromVar) + " <= " + (this.toVar) + " ? " + idx);
+      compare = ("" + intro + " <" + (this.equals) + " " + (this.toVar) + " : " + idx + " >" + (this.equals) + " " + (this.toVar) + ")");
       stepPart = step ? step.compile(o) : '1';
       incr = step ? ("" + idx + " += " + stepPart) : ("" + intro + " += " + stepPart + " : " + idx + " -= " + stepPart + ")");
       return "" + vars + "; " + compare + "; " + incr;
@@ -705,7 +705,7 @@
       idx = del(o, 'index');
       step = del(o, 'step');
       step && (step = ("" + idx + " += " + (step.compile(o))));
-      return from <= to ? ("" + idx + " = " + from + "; " + idx + " <" + this.equals + " " + to + "; " + (step || ("" + idx + "++"))) : ("" + idx + " = " + from + "; " + idx + " >" + this.equals + " " + to + "; " + (step || ("" + idx + "--")));
+      return from <= to ? ("" + idx + " = " + from + "; " + idx + " <" + (this.equals) + " " + to + "; " + (step || ("" + idx + "++"))) : ("" + idx + " = " + from + "; " + idx + " >" + (this.equals) + " " + to + "; " + (step || ("" + idx + "--")));
     };
     RangeNode.prototype.compileArray = function(o) {
       var _i, _ref2, _ref3, _result, body, clause, i, idt, post, pre, range, result, vars;
@@ -731,8 +731,8 @@
         o.index = i;
         body = this.compileSimple(o);
       } else {
-        clause = ("" + this.fromVar + " <= " + this.toVar + " ?");
-        body = ("var " + i + " = " + this.fromVar + "; " + clause + " " + i + " <" + this.equals + " " + this.toVar + " : " + i + " >" + this.equals + " " + this.toVar + "; " + clause + " " + i + " += 1 : " + i + " -= 1");
+        clause = ("" + (this.fromVar) + " <= " + (this.toVar) + " ?");
+        body = ("var " + i + " = " + (this.fromVar) + "; " + clause + " " + i + " <" + (this.equals) + " " + (this.toVar) + " : " + i + " >" + (this.equals) + " " + (this.toVar) + "; " + clause + " " + i + " += 1 : " + i + " -= 1");
       }
       post = ("{ " + result + ".push(" + i + "); }\n" + idt + "return " + result + ";\n" + (o.indent));
       return "(function() {" + pre + "\n" + idt + "for (" + body + ")" + post + "}).call(this)";
@@ -844,7 +844,7 @@
         }
       }
       objects = objects.join('');
-      return indexOf(objects, '\n') >= 0 ? ("[\n" + (this.idt(1)) + objects + "\n" + this.tab + "]") : ("[" + objects + "]");
+      return indexOf(objects, '\n') >= 0 ? ("[\n" + (this.idt(1)) + objects + "\n" + (this.tab) + "]") : ("[" + objects + "]");
     };
     return ArrayNode;
   })();
@@ -977,7 +977,7 @@
       }
       val = ("" + name + " = " + val);
       if (stmt) {
-        return ("" + this.tab + val + ";");
+        return ("" + (this.tab) + val + ";");
       }
       return top || this.parenthetical ? val : ("(" + val + ")");
     };
@@ -1127,7 +1127,7 @@
       code = this.body.expressions.length ? ("\n" + (this.body.compileWithDeclarations(o)) + "\n") : '';
       func = ("function(" + (params.join(', ')) + ") {" + code + (code && this.tab) + "}");
       if (this.bound) {
-        return ("(" + (utility('bind')) + "(" + func + ", " + this.context + "))");
+        return ("(" + (utility('bind')) + "(" + func + ", " + (this.context) + "))");
       }
       return top ? ("(" + func + ")") : func;
     };
@@ -1203,7 +1203,7 @@
           o.scope.assign(trailing.compile(o), "arguments[" + variadic + " ? " + len + " - " + pos + " : " + (this.index + idx) + "]");
         }
       }
-      return "" + name + " = " + (utility('slice')) + ".call(arguments, " + this.index + end + ")";
+      return "" + name + " = " + (utility('slice')) + ".call(arguments, " + (this.index) + end + ")";
     };
     SplatNode.prototype.compileValue = function(o, name, index, trailings) {
       var trail;
@@ -1271,12 +1271,12 @@
       set = '';
       if (!(top)) {
         rvar = o.scope.freeVariable('result');
-        set = ("" + this.tab + rvar + " = [];\n");
+        set = ("" + (this.tab) + rvar + " = [];\n");
         if (this.body) {
           this.body = PushNode.wrap(rvar, this.body);
         }
       }
-      pre = ("" + set + this.tab + "while (" + cond + ")");
+      pre = ("" + set + (this.tab) + "while (" + cond + ")");
       if (this.guard) {
         this.body = Expressions.wrap([new IfNode(this.guard, this.body)]);
       }
@@ -1287,7 +1287,7 @@
       } else {
         post = '';
       }
-      return "" + pre + " {\n" + (this.body.compile(o)) + "\n" + this.tab + "}" + post;
+      return "" + pre + " {\n" + (this.body.compile(o)) + "\n" + (this.tab) + "}" + post;
     };
     return WhileNode;
   })();
@@ -1377,7 +1377,7 @@
       shared = this.first.unwrap().second;
       _ref2 = shared.compileReference(o), this.first.second = _ref2[0], shared = _ref2[1];
       _ref2 = [this.first.compile(o), this.second.compile(o), shared.compile(o)], first = _ref2[0], second = _ref2[1], shared = _ref2[2];
-      return "(" + first + ") && (" + shared + " " + this.operator + " " + second + ")";
+      return "(" + first + ") && (" + shared + " " + (this.operator) + " " + second + ")";
     };
     OpNode.prototype.compileAssignment = function(o) {
       var _ref2, left, rite;
@@ -1446,7 +1446,7 @@
       }), this.arr1 = _ref2[0], this.arr2 = _ref2[1];
       _ref2 = [o.scope.freeVariable('i'), o.scope.freeVariable('len')], i = _ref2[0], l = _ref2[1];
       prefix = this.obj1 !== this.obj2 ? this.obj1 + '; ' : '';
-      return "(function(){ " + prefix + "for (var " + i + "=0, " + l + "=" + this.arr1 + ".length; " + i + "<" + l + "; " + i + "++) { if (" + this.arr2 + "[" + i + "] === " + this.obj2 + ") return true; } return false; }).call(this)";
+      return "(function(){ " + prefix + "for (var " + i + "=0, " + l + "=" + (this.arr1) + ".length; " + i + "<" + l + "; " + i + "++) { if (" + (this.arr2) + "[" + i + "] === " + (this.obj2) + ") return true; } return false; }).call(this)";
     };
     return InNode;
   })();
@@ -1478,9 +1478,9 @@
       o.top = true;
       attemptPart = this.attempt.compile(o);
       errorPart = this.error ? (" (" + (this.error.compile(o)) + ") ") : ' ';
-      catchPart = this.recovery ? (" catch" + errorPart + "{\n" + (this.recovery.compile(o)) + "\n" + this.tab + "}") : '';
-      finallyPart = (this.ensure || '') && ' finally {\n' + this.ensure.compile(merge(o)) + ("\n" + this.tab + "}");
-      return "" + this.tab + "try {\n" + attemptPart + "\n" + this.tab + "}" + catchPart + finallyPart;
+      catchPart = this.recovery ? (" catch" + errorPart + "{\n" + (this.recovery.compile(o)) + "\n" + (this.tab) + "}") : '';
+      finallyPart = (this.ensure || '') && ' finally {\n' + this.ensure.compile(merge(o)) + ("\n" + (this.tab) + "}");
+      return "" + (this.tab) + "try {\n" + attemptPart + "\n" + (this.tab) + "}" + catchPart + finallyPart;
     };
     return TryNode;
   })();
@@ -1496,7 +1496,7 @@
     ThrowNode.prototype.isStatement = YES;
     ThrowNode.prototype.makeReturn = THIS;
     ThrowNode.prototype.compileNode = function(o) {
-      return "" + this.tab + "throw " + (this.expression.compile(o)) + ";";
+      return "" + (this.tab) + "throw " + (this.expression.compile(o)) + ";";
     };
     return ThrowNode;
   })();
@@ -1651,7 +1651,7 @@
         }
       }
       sourcePart = (rvar ? ("" + rvar + " = []; ") : '') + sourcePart;
-      sourcePart = sourcePart ? ("" + this.tab + sourcePart + "\n" + this.tab) : this.tab;
+      sourcePart = sourcePart ? ("" + (this.tab) + sourcePart + "\n" + (this.tab)) : this.tab;
       returnResult = this.compileReturnValue(rvar, o);
       if (!(topLevel)) {
         body = PushNode.wrap(rvar, body);
@@ -1686,7 +1686,7 @@
         top: true
       }));
       vars = range ? name : ("" + name + ", " + ivar);
-      return "" + sourcePart + "for (" + forPart + ") {" + guardPart + "\n" + varPart + body + "\n" + this.tab + "}" + returnResult;
+      return "" + sourcePart + "for (" + forPart + ") {" + guardPart + "\n" + varPart + body + "\n" + (this.tab) + "}" + returnResult;
     };
     return ForNode;
   })();
@@ -1720,7 +1720,7 @@
       var _i, _j, _len, _len2, _ref2, _ref3, block, code, condition, conditions, exprs, idt, pair;
       idt = (o.indent = this.idt(2));
       o.top = true;
-      code = ("" + this.tab + "switch (" + (this.subject.compile(o)) + ") {");
+      code = ("" + (this.tab) + "switch (" + (this.subject.compile(o)) + ") {");
       _ref2 = this.cases;
       for (_i = 0, _len = _ref2.length; _i < _len; _i++) {
         pair = _ref2[_i];
@@ -1742,7 +1742,7 @@
       if (this.otherwise) {
         code += ("\n" + (this.idt(1)) + "default:\n" + (this.otherwise.compile(o)));
       }
-      code += ("\n" + this.tab + "}");
+      code += ("\n" + (this.tab) + "}");
       return code;
     };
     return SwitchNode;
@@ -1828,14 +1828,14 @@
       ifDent = child || (top && !this.isStatement(o)) ? '' : this.idt();
       comDent = child ? this.idt() : '';
       body = this.body.compile(o);
-      ifPart = ("" + ifDent + "if (" + (this.compileCondition(condO)) + ") {\n" + body + "\n" + this.tab + "}");
+      ifPart = ("" + ifDent + "if (" + (this.compileCondition(condO)) + ") {\n" + body + "\n" + (this.tab) + "}");
       if (!(this.elseBody)) {
         return ifPart;
       }
       elsePart = this.isChain ? ' else ' + this.elseBodyNode().compile(merge(o, {
         indent: this.idt(),
         chainChild: true
-      })) : (" else {\n" + (this.elseBody.compile(o)) + "\n" + this.tab + "}");
+      })) : (" else {\n" + (this.elseBody.compile(o)) + "\n" + (this.tab) + "}");
       return "" + ifPart + elsePart;
     };
     IfNode.prototype.compileTernary = function(o) {
diff --git a/lib/optparse.js b/lib/optparse.js
index 3188b2cc..73f79082 100755
--- a/lib/optparse.js
+++ b/lib/optparse.js
@@ -40,7 +40,7 @@
       var _i, _len, _ref, letPart, lines, rule, spaces;
       lines = ['Available options:'];
       if (this.banner) {
-        lines.unshift("" + this.banner + "\n");
+        lines.unshift("" + (this.banner) + "\n");
       }
       _ref = this.rules;
       for (_i = 0, _len = _ref.length; _i < _len; _i++) {
diff --git a/lib/rewriter.js b/lib/rewriter.js
index c079c439..30ab6d63 100644
--- a/lib/rewriter.js
+++ b/lib/rewriter.js
@@ -63,7 +63,7 @@
         } else {
           tokens.splice(i, 0, after);
         }
-      } else if (!('TERMINATOR' === (_ref = ((prev != null) ? prev[0] : undefined)) || 'INDENT' === _ref || 'OUTDENT' === _ref)) {
+      } else if (prev && !('TERMINATOR' === (_ref = prev[0]) || 'INDENT' === _ref || 'OUTDENT' === _ref)) {
         if (((post != null) ? post[0] === 'TERMINATOR' : undefined) && ((after != null) ? after[0] === 'OUTDENT' : undefined)) {
           tokens.splice.apply(tokens, [i + 2, 0].concat(tokens.splice(i, 2)));
           if (tokens[i + 2][0] !== 'TERMINATOR') {
diff --git a/src/lexer.coffee b/src/lexer.coffee
index cbefc874..399abb09 100644
--- a/src/lexer.coffee
+++ b/src/lexer.coffee
@@ -125,8 +125,8 @@ exports.Lexer = class Lexer
         @token 'STRING', (string = match[0]).replace MULTILINER, '\\\n'
       when '"'
         return false unless string = @balancedString @chunk, [['"', '"'], ['#{', '}']]
-        if ~string.indexOf '#{'
-          @interpolateString string
+        if 0 < string.indexOf '#{', 1
+          @interpolateString string.slice 1, -1
         else
           @token 'STRING', @escapeLines string
       else
@@ -142,10 +142,10 @@ exports.Lexer = class Lexer
     heredoc = match[0]
     quote = heredoc.charAt 0
     doc = @sanitizeHeredoc match[2], {quote, indent: null}
-    if quote is '"' and ~doc.indexOf '#{'
-      @interpolateString quote + doc + quote, heredoc: yes
+    if quote is '"' and 0 <= doc.indexOf '#{'
+      @interpolateString doc, heredoc: yes
     else
-      @token 'STRING', quote + @escapeLines(doc, yes) + quote
+      @token 'STRING', @makeString doc, quote, yes
     @line += count heredoc, '\n'
     @i += heredoc.length
     true
@@ -185,19 +185,20 @@ exports.Lexer = class Lexer
   heregexToken: (match) ->
     [heregex, body, flags] = match
     @i += heregex.length
-    unless ~body.indexOf '#{'
+    if 0 > body.indexOf '#{'
       re = body.replace(HEREGEX_OMIT, '').replace(/\//g, '\\/')
       @token 'REGEX', "/#{ re or '(?:)' }/#{flags}"
       return true
     @token 'IDENTIFIER', 'RegExp'
     @tokens.push ['CALL_START', '(']
     tokens = []
-    for [tag, value] in @interpolateString('"' + body + '"', regex: yes)
+    for [tag, value] in @interpolateString(body, regex: yes)
       if tag is 'TOKENS'
         tokens.push value...
       else
-        continue unless value = value.slice(1, -1).replace HEREGEX_OMIT, ''
-        tokens.push ['STRING', '"' + value.replace(/[\\\"]/g, '\\$&') + '"']
+        continue unless value = value.replace HEREGEX_OMIT, ''
+        value = value.replace /\\/g, '\\\\'
+        tokens.push ['STRING', @makeString(value, '"', yes)]
       tokens.push ['+', '+']
     tokens.pop()
     @tokens.push ['STRING', '""'], ['+', '+'] unless tokens[0]?[0] is 'STRING'
@@ -344,22 +345,17 @@ exports.Lexer = class Lexer
       prev[0] is '@'
     if accessor then 'accessor' else false
 
-  # Sanitize a heredoc or herecomment by escaping internal double quotes and
+  # Sanitize a heredoc or herecomment by
   # erasing all external indentation on the left-hand side.
   sanitizeHeredoc: (doc, options) ->
     {indent, herecomment} = options
-    return doc if herecomment and not include doc, '\n'
+    return doc if herecomment and 0 > doc.indexOf '\n'
     unless herecomment
-      while (match = HEREDOC_INDENT.exec doc)
+      while match = HEREDOC_INDENT.exec doc
         attempt = match[1]
         indent = attempt if indent is null or 0 < attempt.length < indent.length
     doc = doc.replace /// \n #{indent} ///g, '\n' if indent
-    return doc if herecomment
-    {quote} = options
-    doc = doc.replace /^\n/, ''
-    doc = doc.replace /\\([\s\S])/g, (m, c) -> if c in ['\n', quote] then c else m
-    doc = doc.replace /// #{quote} ///g, '\\$&'
-    doc = @escapeLines doc, yes if quote is "'"
+    doc = doc.replace /^\n/, '' unless herecomment
     doc
 
   # A source of ambiguity in our grammar used to be parameter lists in function
@@ -429,12 +425,10 @@ exports.Lexer = class Lexer
   # new Lexer, tokenize the interpolated contents, and merge them into the
   # token stream.
   interpolateString: (str, options) ->
-    return @token 'STRING', @escapeLines(str, heredoc) if str.length < 5  # "#{}"
     {heredoc, regex} = options or= {}
-    lexer  = new Lexer
     tokens = []
-    pi = 1
-    i  = 0
+    pi = 0
+    i  = -1
     while char = str.charAt i += 1
       if char is '\\'
         i += 1
@@ -442,28 +436,28 @@ exports.Lexer = class Lexer
       unless char is '#' and str.charAt(i+1) is '{' and
              (expr = @balancedString str[i+1..], [['{', '}']])
         continue
-      tokens.push ['STRING', '"' + str[pi...i] + '"'] if pi < i
+      tokens.push ['TO_BE_STRING', str[pi...i]] if pi < i
       inner = expr.slice(1, -1).replace(LEADING_SPACES, '').replace(TRAILING_SPACES, '')
       if inner.length
-        inner = inner.replace /\\\"/g, '"' if heredoc
-        nested = lexer.tokenize "(#{inner}\n)", line: @line
-        (tok[0] = ')') for tok in nested when tok[0] is 'CALL_END'
+        nested = new Lexer().tokenize inner, line: @line, rewrite: off
         nested.pop()
-        if nested.length < 5 then nested.pop(); nested.shift()
+        if nested.length > 1
+          nested.unshift ['(', '(']
+          nested.push    [')', ')']
         tokens.push ['TOKENS', nested]
       i += expr.length
       pi = i + 1
-    tokens.push ['STRING', '"' + str.slice pi] if i > pi < str.length - 1
+    tokens.push ['TO_BE_STRING', str[pi..]] if i > pi < str.length
     return tokens if regex
-    interpolated = tokens.length > 1
-    tokens.unshift ['STRING', '""'] unless tokens[0]?[0] is 'STRING'
-    @token '(', '(' if interpolated
+    return @token 'STRING', '""' unless tokens.length
+    @token '(', '(' if interpolated = tokens.length > 1
+    @tokens.push ['STRING', '""'], ['+', '+'] unless tokens[0][0] is 'TO_BE_STRING'
     for [tag, value], i in tokens
       @token '+', '+' if i
       if tag is 'TOKENS'
         @tokens.push value...
       else
-        @token tag, @escapeLines value, heredoc
+        @token 'STRING', @makeString value, '"', heredoc
     @token ')', ')' if interpolated
     tokens
 
@@ -494,6 +488,13 @@ exports.Lexer = class Lexer
   escapeLines: (str, heredoc) ->
     str.replace MULTILINER, if heredoc then '\\n' else ''
 
+  # Constructs a string token by escaping quotes and newlines.
+  makeString: (body, quote, heredoc) ->
+    body = body.replace /\\([\s\S])/g, ($amp, $1) ->
+      if $1 in ['\n', quote] then $1 else $amp
+    body = body.replace /// #{quote} ///g, '\\$&'
+    quote + @escapeLines(body, heredoc) + quote
+
 # Constants
 # ---------
 
@@ -535,7 +536,7 @@ JS_FORBIDDEN = JS_KEYWORDS.concat RESERVED
 # Token matching regexes.
 IDENTIFIER = /^[a-zA-Z_$][\w$]*/
 NUMBER     = /^0x[\da-f]+|^(?:\d+(\.\d+)?|\.\d+)(?:e[+-]?\d+)?/i
-HEREDOC    = /^("""|''')([\s\S]*?)\n?[ \t]*\1/
+HEREDOC    = /^("""|''')([\s\S]*?)(?:\n[ \t]*)?\1/
 OPERATOR   = /^(?:-[-=>]?|\+[+=]?|[*&|\/%=<>^:!?]+)(?=([ \t]*))/
 WHITESPACE = /^[ \t]+/
 COMMENT    = /^###([^#][\s\S]*?)(?:###[ \t]*\n|(?:###)?$)|^(?:\s*#(?!##[^#]).*)+/
diff --git a/src/rewriter.coffee b/src/rewriter.coffee
index 70ea972f..3cb57c6c 100644
--- a/src/rewriter.coffee
+++ b/src/rewriter.coffee
@@ -73,7 +73,7 @@ class exports.Rewriter
           tokens.splice i - 2, 1
         else
           tokens.splice i, 0, after
-      else if prev?[0] not in ['TERMINATOR', 'INDENT', 'OUTDENT']
+      else if prev and prev[0] not in ['TERMINATOR', 'INDENT', 'OUTDENT']
         if post?[0] is 'TERMINATOR' and after?[0] is 'OUTDENT'
           tokens.splice i + 2, 0, tokens.splice(i, 2)...
           if tokens[i + 2][0] isnt 'TERMINATOR'
diff --git a/test/test_heredocs.coffee b/test/test_heredocs.coffee
index 5c727483..330ecdf7 100644
--- a/test/test_heredocs.coffee
+++ b/test/test_heredocs.coffee
@@ -89,8 +89,7 @@ a = """
     """
 ok a is "one\ntwo\n"
 
-
-equal ''' line 0
+eq ''' line 0
   should not be relevant
     to the indent level
 ''', '
@@ -99,10 +98,14 @@ should not be relevant\n
   to the indent level
 '
 
+eq ''' '\\\' ''', " '\\' "
+eq """ "\\\" """, ' "\\" '
 
-equal 'multiline nested interpolations work', """multiline #{
+eq '''  <- keep these spaces ->  ''', '  <- keep these spaces ->  '
+
+eq 'multiline nested "interpolations" work', """multiline #{
   "nested #{(->
     ok yes
-    "interpolations"
+    "\"interpolations\""
   )()}"
 } work"""
diff --git a/test/test_regexps.coffee b/test/test_regexps.coffee
index 759f75e7..e78e89de 100644
--- a/test/test_regexps.coffee
+++ b/test/test_regexps.coffee
@@ -25,11 +25,12 @@ ok (obj.width()/id - obj.height()/id) is -5
 eq /^I'm\s+Heregex?\/\/\//gim + '', ///
   ^ I'm \s+ Heregex? / // # or not
 ///gim + ''
-eq '\\\\#{}', ///
+eq '\\\\#{}\\\\\\\"', ///
  #{
    "#{ '\\' }" # normal comment
  }
  # regex comment
  \#{}
+ \\ \"
 ///.source
 eq ///  /// + '', '/(?:)/'