Unable to install serverless on mac OSX

Hi there,
Actually I’m unable to install serverless on my Mac. Here are some information :
OSX Yosemite 10.10.5
Node Js 6.2.10
Npm 3.10.10

Command to install serveless : sudo npm -g install serverless

result :
/usr/local/bin/serverless -> /usr/local/lib/node_modules/serverless/bin/serverless
/usr/local/bin/slss -> /usr/local/lib/node_modules/serverless/bin/serverless
/usr/local/bin/sls -> /usr/local/lib/node_modules/serverless/bin/serverless

serverless@1.11.0 postinstall /usr/local/lib/node_modules/serverless
node ./scripts/postinstall.js

Unhandled rejection SyntaxError: Unexpected token \ in JSON at position 1
at Object.parse (native)
at exports.parse (/usr/local/lib/node_modules/serverless/node_modules/rc/lib/utils.js:15:17)
at addConfigFile (/usr/local/lib/node_modules/serverless/node_modules/rc/index.js:31:20)
at Array.forEach (native)
at module.exports (/usr/local/lib/node_modules/serverless/node_modules/rc/index.js:44:36)
at Object. (/usr/local/lib/node_modules/serverless/node_modules/get-proxy/index.js:2:25)
at Module._compile (module.js:570:32)
at Object.Module._extensions…js (module.js:579:10)
at Module.load (module.js:487:32)
at tryModuleLoad (module.js:446:12)
at Function.Module._load (module.js:438:3)
at Module.require (module.js:497:17)
at require (internal/module.js:20:19)
at Object. (/usr/local/lib/node_modules/serverless/node_modules/caw/index.js:3:18)
at Module._compile (module.js:570:32)
at Object.Module._extensions…js (module.js:579:10)

Could someone help me please ?