diff --git a/lib/entry-index.js b/lib/entry-index.js
index a158837..bb7bb89 100644
--- a/lib/entry-index.js
+++ b/lib/entry-index.js
@@ -1,104 +1,106 @@
 'use strict'
 
-var asyncMap = require('slide/lib/async-map')
-var contentPath = require('./content/path')
-var fixOwner = require('./util/fix-owner')
-var fs = require('graceful-fs')
-var lockfile = require('lockfile')
-var path = require('path')
-var pipe = require('mississippi').pipe
-var split = require('split')
-var through = require('mississippi').through
+const asyncMap = require('slide/lib/async-map')
+const contentPath = require('./content/path')
+const fixOwner = require('./util/fix-owner')
+const fs = require('graceful-fs')
+const lockfile = require('lockfile')
+const path = require('path')
+const pipe = require('mississippi').pipe
+const Promise = require('bluebird')
+const split = require('split')
+const through = require('mississippi').through
 
 module.exports.insert = insert
-function insert (cache, key, digest, opts, _cb) {
-  if (!_cb) {
-    _cb = opts
-    opts = null
-  }
+function insert (cache, key, digest, opts) {
   opts = opts || {}
-  var bucket = indexPath(cache, key)
-  var lock = bucket + '.lock'
-  var cb = function (err, entry) {
-    lockfile.unlock(lock, function (er) {
-      _cb(er || err, entry)
-    })
-  }
-  fixOwner.mkdirfix(path.dirname(bucket), opts.uid, opts.gid, function (err) {
-    if (err) { return _cb(err) }
-    lockfile.lock(lock, {
-      stale: 60000,
-      retries: 10,
-      wait: 10000
-    }, function (err) {
-      if (err) { return _cb(err) }
-      fs.stat(bucket, function (err, existing) {
-        if (err && err.code !== 'ENOENT' && err.code !== 'EPERM') { cb(err) }
-        var entry = {
-          key: key,
-          digest: digest,
-          time: +(new Date()),
-          metadata: opts.metadata
-        }
-        // Because of the way these entries work,
-        // the index is safe from fs.appendFile stopping
-        // mid-write so long as newlines are *prepended*
-        //
-        // That is, if a write fails, it will be ignored
-        // by `find`, and the next successful one will be
-        // used.
-        //
-        // This should be -very rare-, since `fs.appendFile`
-        // will often be atomic on most platforms unless
-        // very large metadata has been included, but caches
-        // like this one tend to last a long time. :)
-        // Most corrupted reads are likely to be from attempting
-        // to read the index while it's being written to --
-        // which is safe, but not guaranteed to be atomic.
-        var e = (existing ? '\n' : '') + JSON.stringify(entry)
-        fs.appendFile(bucket, e, function (err) {
-          if (err) { return cb(err) }
-          fixOwner.chownr(bucket, opts.uid, opts.gid, function (err) {
+  const bucket = indexPath(cache, key)
+  const lock = bucket + '.lock'
+  return fixOwner.mkdirfix(
+    path.dirname(bucket), opts.uid, opts.gid
+  ).then(() => (
+    Promise.fromNode(_cb => {
+      const cb = (err, entry) => {
+        lockfile.unlock(lock, er => {
+          _cb(err || er, entry)
+        })
+      }
+      lockfile.lock(lock, {
+        stale: 60000,
+        retries: 10,
+        wait: 10000
+      }, function (err) {
+        if (err) { return _cb(err) }
+        fs.stat(bucket, function (err, existing) {
+          if (err && err.code !== 'ENOENT' && err.code !== 'EPERM') {
+            return cb(err)
+          }
+          const entry = {
+            key: key,
+            digest: digest,
+            time: +(new Date()),
+            metadata: opts.metadata
+          }
+          // Because of the way these entries work,
+          // the index is safe from fs.appendFile stopping
+          // mid-write so long as newlines are *prepended*
+          //
+          // That is, if a write fails, it will be ignored
+          // by `find`, and the next successful one will be
+          // used.
+          //
+          // This should be -very rare-, since `fs.appendFile`
+          // will often be atomic on most platforms unless
+          // very large metadata has been included, but caches
+          // like this one tend to last a long time. :)
+          // Most corrupted reads are likely to be from attempting
+          // to read the index while it's being written to --
+          // which is safe, but not guaranteed to be atomic.
+          const e = (existing ? '\n' : '') + JSON.stringify(entry)
+          fs.appendFile(bucket, e, function (err) {
             cb(err, entry)
           })
         })
       })
     })
-  })
+  )).then(() => fixOwner.chownr(bucket, opts.uid, opts.gid))
 }
 
 module.exports.find = find
-function find (cache, key, cb) {
-  var bucket = indexPath(cache, key)
-  var stream = fs.createReadStream(bucket)
-  var ret
-  pipe(stream, split('\n', null, {trailing: true}).on('data', function (l) {
-    try {
-      var obj = JSON.parse(l)
-    } catch (e) {
-      return
-    }
-    if (obj && (obj.key === key)) {
-      ret = formatEntry(cache, obj)
-    }
-  }), function (err) {
-    if (err && err.code === 'ENOENT') {
-      cb(null, null)
-    } else {
-      cb(err, ret)
-    }
+function find (cache, key) {
+  const bucket = indexPath(cache, key)
+  const stream = fs.createReadStream(bucket)
+  let ret
+  return Promise.fromNode(cb => {
+    pipe(stream, split('\n', null, {trailing: true}).on('data', function (l) {
+      let obj
+      try {
+        obj = JSON.parse(l)
+      } catch (e) {
+        return
+      }
+      if (obj && (obj.key === key)) {
+        ret = formatEntry(cache, obj)
+      }
+    }), function (err) {
+      if (err && err.code === 'ENOENT') {
+        cb(null, null)
+      } else {
+        cb(err, ret)
+      }
+    })
   })
 }
 
 module.exports.delete = del
-function del (cache, key, cb) {
-  insert(cache, key, null, cb)
+function del (cache, key) {
+  return insert(cache, key, null)
 }
 
 module.exports.lsStream = lsStream
 function lsStream (cache) {
-  var indexPath = path.join(cache, 'index')
-  var stream = through.obj()
+  const indexPath = path.join(cache, 'index')
+  const stream = through.obj()
   fs.readdir(indexPath, function (err, files) {
     if (err && err.code === 'ENOENT') {
       return stream.end()
@@ -108,10 +110,11 @@ function lsStream (cache) {
       asyncMap(files, function (f, cb) {
         fs.readFile(path.join(indexPath, f), 'utf8', function (err, data) {
           if (err) { return cb(err) }
-          var entries = {}
+          const entries = {}
           data.split('\n').forEach(function (entry) {
+            let parsed
             try {
-              var parsed = JSON.parse(entry)
+              parsed = JSON.parse(entry)
             } catch (e) {
             }
             // NOTE - it's possible for an entry to be
@@ -136,18 +139,20 @@ function lsStream (cache) {
 }
 
 module.exports.ls = ls
-function ls (cache, cb) {
-  var entries = {}
-  lsStream(cache).on('finish', function () {
-    cb(null, entries)
-  }).on('data', function (d) {
-    entries[d.key] = d
-  }).on('error', cb)
+function ls (cache) {
+  const entries = {}
+  return Promise.fromNode(cb => {
+    lsStream(cache).on('finish', function () {
+      cb(null, entries)
+    }).on('data', function (d) {
+      entries[d.key] = d
+    }).on('error', cb)
+  })
 }
 
 module.exports.notFoundError = notFoundError
 function notFoundError (cache, key) {
-  var err = new Error('content not found')
+  const err = new Error('content not found')
   err.code = 'ENOENT'
   err.cache = cache
   err.key = key