npm windows missing write access

I'm getting this message

npm WARN checkPermissions Missing Write Access to D:\my\path\node_module\bcrypt

while installing bcrypt package using npm i bcrypt

I tried executing the commands from cmd as an administrator and also from powershell, nothing worked. I also cleared the cache npm cache clean and manually deleted %AppData%/npm_cache directory.

I'm using:
npm 3.7.3
node 5.9.1
windows 7

Why isn't npm getting the permission to write?

Note that npm can install and write other modules(i.e angular2,mongoose,express etc) just fine.