diff --git a/bin/6to5/index.js b/bin/6to5/index.js
index 84cfa2db0b..f4bb9e9ed3 100755
--- a/bin/6to5/index.js
+++ b/bin/6to5/index.js
@@ -21,6 +21,7 @@ commander.option("-i, --optional [list]", "List of optional transformers to enab
 commander.option("-o, --out-file [out]", "Compile all input files into a single file");
 commander.option("-d, --out-dir [out]", "Compile an input directory of modules into an output directory");
 commander.option("-c, --remove-comments", "Remove comments from the compiled code", false);
+commander.option("-I, --indent [width]", "Indent width [2]", 2);
 commander.option("-a, --amd-module-ids", "Insert module id in AMD modules", false); // todo: remove in 3.0.0
 commander.option("-m, --module-ids", "Insert module id in modules", false);
 
@@ -108,7 +109,12 @@ exports.opts = {
   optional:      commander.optional,
   comments:      !commander.removeComments,
   runtime:       commander.runtime,
-  modules:       commander.modules
+  modules:       commander.modules,
+  format: {
+    indent: {
+      style:     util.repeat(parseInt(commander.indent))
+    }
+  }
 };
 
 var fn;