diff --git a/lib/coffee-script.js b/lib/coffee-script.js
index eb6b2ae78d..84a7c3b7bf 100755
--- a/lib/coffee-script.js
+++ b/lib/coffee-script.js
@@ -62,7 +62,7 @@
     }
   };
   exports.eval = function(code, options) {
-    var js, k, o, r, sandbox, v, _, _i, _len, _module, _ref2, _ref3, _require;
+    var js, k, o, r, returnValue, sandbox, v, _, _i, _len, _module, _ref2, _ref3, _require;
     if (options == null) {
       options = {};
     }
@@ -109,12 +109,13 @@
       o[k] = v;
     }
     o.bare = true;
-    js = compile("(" + code + "\n)", o);
-    _ = Script.runInContext(js, sandbox);
-    if (_ != null) {
+    js = compile("_=(" + code + "\n)", o);
+    _ = sandbox._;
+    returnValue = Script.runInContext(js, sandbox);
+    if (returnValue === void 0) {
       sandbox._ = _;
     }
-    return _;
+    return returnValue;
   };
   lexer = new Lexer;
   parser.lexer = {
diff --git a/src/coffee-script.coffee b/src/coffee-script.coffee
index 9fb30d50b6..c5fc8251b1 100755
--- a/src/coffee-script.coffee
+++ b/src/coffee-script.coffee
@@ -101,10 +101,11 @@ exports.eval = (code, options = {}) ->
   o = {}
   o[k] = v for own k, v of options
   o.bare = on # ensure return value
-  js = compile "(#{code}\n)", o
-  _ = Script.runInContext js, sandbox
-  sandbox._ = _ if _?
-  _
+  js = compile "_=(#{code}\n)", o
+  _ = sandbox._
+  returnValue = Script.runInContext js, sandbox
+  sandbox._ = _ if returnValue is undefined
+  returnValue
 
 # Instantiate a Lexer for our use here.
 lexer = new Lexer