diff --git a/index.js b/index.js
index b0ea403..d07ead9 100644
--- a/index.js
+++ b/index.js
@@ -1,4 +1,4 @@
-const mutexify = require('mutexify')
+const mutexify = require('mutexify/promise')
 const b4a = require('b4a')
 
 const { BlobReadStream, BlobWriteStream } = require('./lib/streams')
@@ -11,7 +11,6 @@ module.exports = class Hyperblobs {
     this.blockSize = opts.blockSize || DEFAULT_BLOCK_SIZE
 
     this._lock = mutexify()
-    this._core = core
   }
 
   get feed () {
@@ -59,12 +58,12 @@ module.exports = class Hyperblobs {
   }
 
   createReadStream (id, opts) {
-    const core = (opts && opts.core) ? opts.core : this._core
+    const core = (opts && opts.core) ? opts.core : this.core
     return new BlobReadStream(core, id, opts)
   }
 
   createWriteStream (opts) {
-    const core = (opts && opts.core) ? opts.core : this._core
+    const core = (opts && opts.core) ? opts.core : this.core
     return new BlobWriteStream(core, this._lock, opts)
   }
 }
diff --git a/lib/streams.js b/lib/streams.js
index b315290..cffcbad 100644
--- a/lib/streams.js
+++ b/lib/streams.js
@@ -10,6 +10,7 @@ class SparsePrefetcher {
   prefetch (bounds, index) {
     const startBlock = bounds.blockOffset
     const endBlock = startBlock + bounds.blockLength
+
     return {
       start: Math.max(index, startBlock),
       end: Math.min(index + this._length, endBlock),
@@ -18,50 +19,28 @@ class SparsePrefetcher {
   }
 }
 
-/* eslint-disable no-unused-vars */
-class EagerPrefetcher {
-  constructor (opts = {}) {
-    this._linear = opts.linear !== false
-    this._done = false
-  }
-
-  prefetch (bounds) {
-    if (this._done) return null
-    this._done = true
-    const startBlock = bounds.blockOffset
-    const endBlock = startBlock + bounds.blockLength
-    return { start: startBlock, end: endBlock, linear: this._linear }
-  }
-}
-
 class BlobWriteStream extends Writable {
   constructor (core, lock, opts) {
     super(opts)
-    this.id = {}
+
     this.core = core
+    this.id = { byteOffset: 0, blockOffset: 0, blockLength: 0, byteLength: 0 }
+
     this._lock = lock
     this._release = null
     this._batch = []
   }
 
   _open (cb) {
-    this.core.ready().then(() => {
-      this._lock(release => {
-        this._release = release
-        this.id.byteOffset = this.core.byteLength
-        this.id.blockOffset = this.core.length
-        return cb(null)
-      })
-    }, err => cb(err))
+    this._openp().then(cb, cb)
+  }
+
+  _write (data, cb) {
+    this._writep(data).then(cb, cb)
   }
 
   _final (cb) {
-    this._append(err => {
-      if (err) return cb(err)
-      this.id.blockLength = this.core.length - this.id.blockOffset
-      this.id.byteLength = this.core.byteLength - this.id.byteOffset
-      return cb(null)
-    })
+    this._finalp().then(cb, cb)
   }
 
   _destroy (cb) {
@@ -69,29 +48,45 @@ class BlobWriteStream extends Writable {
     cb(null)
   }
 
-  _append (cb) {
-    if (!this._batch.length) return cb(null)
-    return this.core.append(this._batch).then(() => {
-      this._batch = []
-      return cb(null)
-    }, err => {
-      this._batch = []
-      return cb(err)
-    })
+  async _openp () {
+    await this.core.ready()
+
+    this._release = await this._lock()
+
+    this.id.byteOffset = this.core.byteLength
+    this.id.blockOffset = this.core.length
   }
 
-  _write (data, cb) {
+  async _writep (data) {
     this._batch.push(data)
-    if (this._batch.length >= 16) return this._append(cb)
-    return cb(null)
+
+    if (this._batch.length >= 16) await this._append()
+  }
+
+  async _finalp () {
+    await this._append()
+
+    this.id.blockLength = this.core.length - this.id.blockOffset
+    this.id.byteLength = this.core.byteLength - this.id.byteOffset
+  }
+
+  async _append () {
+    if (!this._batch.length) return
+
+    try {
+      await this.core.append(this._batch)
+    } finally {
+      this._batch = []
+    }
   }
 }
 
 class BlobReadStream extends Readable {
   constructor (core, id, opts = {}) {
     super(opts)
-    this.id = id
+
     this.core = core.session({ wait: opts.wait, timeout: opts.timeout })
+    this.id = id
 
     this._prefetch = opts.wait === false ? noPrefetch : opts.prefetch
     this._lastPrefetch = null
@@ -112,22 +107,11 @@ class BlobReadStream extends Readable {
   }
 
   _open (cb) {
-    if (this._pos === this.id.byteOffset) {
-      this._index = this.id.blockOffset
-      this._relativeOffset = 0
-      return cb(null)
-    }
-
-    this.core.seek(this._pos, {
-      start: this.id.blockOffset,
-      end: this.id.blockOffset + this.id.blockLength
-    }).then(result => {
-      if (!result) return cb(BLOCK_NOT_AVAILABLE())
+    this._openp().then(cb, cb)
+  }
 
-      this._index = result[0]
-      this._relativeOffset = result[1]
-      return cb(null)
-    }, err => cb(err))
+  _read (cb) {
+    this._readp().then(cb, cb)
   }
 
   _predestroy () {
@@ -138,10 +122,28 @@ class BlobReadStream extends Readable {
     this.core.close().then(cb, cb)
   }
 
-  _read (cb) {
+  async _openp (cb) {
+    if (this._pos === this.id.byteOffset) {
+      this._index = this.id.blockOffset
+      this._relativeOffset = 0
+      return
+    }
+
+    const seek = await this.core.seek(this._pos, {
+      start: this.id.blockOffset,
+      end: this.id.blockOffset + this.id.blockLength
+    })
+
+    if (!seek) throw BLOCK_NOT_AVAILABLE()
+
+    this._index = seek[0]
+    this._relativeOffset = seek[1]
+  }
+
+  async _readp (cb) {
     if (this._pos >= this._end) {
       this.push(null)
-      return cb(null)
+      return
     }
 
     const prefetch = this._prefetch(this.id, this._index)
@@ -150,22 +152,20 @@ class BlobReadStream extends Readable {
       this._lastPrefetch = this.core.download(prefetch)
     }
 
-    this.core.get(this._index).then(block => {
-      if (!block) return cb(BLOCK_NOT_AVAILABLE())
+    let block = await this.core.get(this._index)
+    if (!block) throw BLOCK_NOT_AVAILABLE()
 
-      const remainder = this._end - this._pos
-      if (this._relativeOffset || (remainder < block.length)) {
-        block = block.subarray(this._relativeOffset, this._relativeOffset + remainder)
-      }
+    const remainder = this._end - this._pos
+    if (this._relativeOffset || (remainder < block.length)) {
+      block = block.subarray(this._relativeOffset, this._relativeOffset + remainder)
+    }
 
-      this._index++
-      this._relativeOffset = 0
-      this._pos += block.length
-      this._bytesRead += block.length
+    this._index++
+    this._relativeOffset = 0
+    this._pos += block.length
+    this._bytesRead += block.length
 
-      this.push(block)
-      return cb(null)
-    }, err => cb(err))
+    this.push(block)
   }
 }
 
diff --git a/package.json b/package.json
index 37140bd..e946376 100644
--- a/package.json
+++ b/package.json
@@ -25,7 +25,7 @@
     "b4a": "^1.6.1",
     "hypercore-errors": "^1.0.0",
     "mutexify": "^1.4.0",
-    "streamx": "^2.13.2"
+    "streamx": "^2.15.0"
   },
   "devDependencies": {
     "brittle": "^3.1.0",