diff --git a/README.md b/README.md
index e50d98e6e3..6d5398ca23 100644
--- a/README.md
+++ b/README.md
@@ -50,8 +50,7 @@ object referring to that same position.
 
 - **ecmaVersion**: Indicates the ECMAScript version to parse. Must be
   either 3, 5, or 6. This influences support for strict mode, the set
-  of reserved words, and support for getters and setter. Default is 5.
-  ES6 is only partially supported.
+  of reserved words, and support for new syntax features. Default is 5.
 
 - **strictSemicolons**: If `true`, prevents the parser from doing
   automatic semicolon insertion, and statements that do not end with
diff --git a/bin/acorn b/bin/acorn
index d5e5e3a511..2a226da063 100755
--- a/bin/acorn
+++ b/bin/acorn
@@ -8,7 +8,7 @@ var infile, parsed, options = {}, silent = false, compact = false;
 
 function help(status) {
   var print = (status == 0) ? console.log : console.error;
-  print("usage: " + path.basename(process.argv[1]) + " [--ecma3|--ecma5] [--strictSemicolons]");
+  print("usage: " + path.basename(process.argv[1]) + " [--ecma3|--ecma5|--ecma6] [--strictSemicolons]");
   print("        [--locations] [--compact] [--silent] [--help] [--] infile");
   process.exit(status);
 }
@@ -19,6 +19,7 @@ for (var i = 2; i < process.argv.length; ++i) {
   else if (arg == "--" && !infile && i + 2 == process.argv.length) infile = process.argv[++i];
   else if (arg == "--ecma3") options.ecmaVersion = 3;
   else if (arg == "--ecma5") options.ecmaVersion = 5;
+  else if (arg == "--ecma6") options.ecmaVersion = 6;
   else if (arg == "--strictSemicolons") options.strictSemicolons = true;
   else if (arg == "--locations") options.locations = true;
   else if (arg == "--silent") silent = true;