diff --git a/app/api.js b/app/api.js
index 876756ba..d8cd9b9b 100644
--- a/app/api.js
+++ b/app/api.js
@@ -100,8 +100,30 @@ function asyncInitWebSocket(server) {
   });
 }
 
+function listenForResponse(ws, canceller) {
+  return new Promise((resolve, reject) => {
+    ws.addEventListener('message', function(msg) {
+      try {
+        const response = JSON.parse(msg.data);
+        if (response.error) {
+          throw new Error(response.error);
+        } else {
+          resolve({
+            url: response.url,
+            id: response.id,
+            ownerToken: response.owner
+          });
+        }
+      } catch (e) {
+        canceller.cancelled = true;
+        canceller.error = e;
+        reject(e);
+      }
+    });
+  });
+}
+
 async function upload(
-  ws,
   stream,
   streamInfo,
   metadata,
@@ -110,55 +132,51 @@ async function upload(
   onprogress,
   canceller
 ) {
-  const metadataHeader = arrayToB64(new Uint8Array(metadata));
-  const fileMeta = {
-    fileMetadata: metadataHeader,
-    authorization: `send-v1 ${verifierB64}`
-  };
+  const host = window.location.hostname;
+  const port = window.location.port;
+  const protocol = window.location.protocol === 'https:' ? 'wss:' : 'ws:';
+  const error = { cancelled: false };
+  const ws = await asyncInitWebSocket(`${protocol}//${host}:${port}/api/ws`);
 
-  function listenForResponse() {
-    return new Promise((resolve, reject) => {
-      ws.addEventListener('message', function(msg) {
-        const response = JSON.parse(msg.data);
-        if (response.error) {
-          reject(response.error);
-        } else {
-          resolve({
-            url: response.url,
-            id: response.id,
-            ownerToken: response.owner
-          });
-        }
-      });
-    });
-  }
+  try {
+    const metadataHeader = arrayToB64(new Uint8Array(metadata));
+    const fileMeta = {
+      fileMetadata: metadataHeader,
+      authorization: `send-v1 ${verifierB64}`
+    };
 
-  const resPromise = listenForResponse();
-  ws.send(JSON.stringify(fileMeta));
+    const responsePromise = listenForResponse(ws, error);
 
-  const reader = stream.getReader();
-  let state = await reader.read();
-  let size = 0;
-  while (!state.done) {
-    const buf = state.value;
-    if (canceller.cancelled) {
-      ws.close(4000, 'upload cancelled');
-      throw new Error(0);
+    ws.send(JSON.stringify(fileMeta));
+
+    const reader = stream.getReader();
+    let state = await reader.read();
+    let size = 0;
+    while (!state.done) {
+      const buf = state.value;
+      if (canceller.cancelled) {
+        throw new Error(0);
+      }
+      if (error.cancelled) {
+        throw new Error(error.error);
+      }
+      ws.send(buf);
+
+      onprogress([Math.min(streamInfo.fileSize, size), streamInfo.fileSize]);
+      size += streamInfo.recordSize;
+      state = await reader.read();
     }
-    ws.send(buf);
 
-    onprogress([Math.min(streamInfo.fileSize, size), streamInfo.fileSize]);
-    size += streamInfo.recordSize;
-    state = await reader.read();
+    const response = await responsePromise; //promise only fufills if response is good
+    ws.close();
+    return response;
+  } catch (e) {
+    ws.close(4000);
+    throw e;
   }
-
-  const response = await resPromise;
-
-  ws.close();
-  return response;
 }
 
-export async function uploadWs(
+export function uploadWs(
   encrypted,
   info,
   metadata,
@@ -166,10 +184,6 @@ export async function uploadWs(
   keychain,
   onprogress
 ) {
-  const host = window.location.hostname;
-  const port = window.location.port;
-  const protocol = window.location.protocol === 'https:' ? 'wss:' : 'ws:';
-  const ws = await asyncInitWebSocket(`${protocol}//${host}:${port}/api/ws`);
   const canceller = { cancelled: false };
 
   return {
@@ -177,7 +191,6 @@ export async function uploadWs(
       canceller.cancelled = true;
     },
     result: upload(
-      ws,
       encrypted,
       info,
       metadata,
diff --git a/app/ece.js b/app/ece.js
index c962106a..eb86c6c0 100644
--- a/app/ece.js
+++ b/app/ece.js
@@ -282,11 +282,11 @@ export default class ECE {
 
     this.streamInfo = {
       recordSize: rs,
-      fileSize: input.size + 16 * Math.floor(input.size / (rs - 17))
+      fileSize: 21 + input.size + 16 * Math.floor(input.size / (rs - 17))
     };
-    input = new BlobSliceStream(input, rs, mode);
+    const inputStream = new BlobSliceStream(input, rs, mode);
 
     const ts = new TransformStream(new ECETransformer(mode, key, rs, salt));
-    this.stream = input.pipeThrough(ts);
+    this.stream = inputStream.pipeThrough(ts);
   }
 }
diff --git a/app/fileReceiver.js b/app/fileReceiver.js
index d35123c4..385b749b 100644
--- a/app/fileReceiver.js
+++ b/app/fileReceiver.js
@@ -51,25 +51,18 @@ export default class FileReceiver extends Nanobus {
     this.state = 'ready';
   }
 
-  async streamToArrayBuffer(stream) {
+  async streamToArrayBuffer(stream, streamSize) {
     const reader = stream.getReader();
-    const chunks = [];
-    let length = 0;
+    const result = new Int8Array(streamSize);
+    let offset = 0;
 
     let state = await reader.read();
     while (!state.done) {
-      chunks.push(state.value);
-      length += state.value.length;
+      result.set(state.value, offset);
+      offset += state.value.length;
       state = await reader.read();
     }
 
-    const result = new Int8Array(length);
-    let offset = 0;
-    for (let i = 0; i < chunks.length; i++) {
-      result.set(chunks[i], offset);
-      offset += chunks[i].length;
-    }
-
     return result.buffer;
   }
 
@@ -93,8 +86,10 @@ export default class FileReceiver extends Nanobus {
 
       const dec = await this.keychain.decryptStream(ciphertext);
       const plainstream = dec.stream;
-
-      const plaintext = await this.streamToArrayBuffer(plainstream);
+      const plaintext = await this.streamToArrayBuffer(
+        plainstream,
+        dec.streamInfo.fileSize
+      );
 
       if (!noSave) {
         await saveFile({
diff --git a/app/fileSender.js b/app/fileSender.js
index 71b416c9..4f0a64a4 100644
--- a/app/fileSender.js
+++ b/app/fileSender.js
@@ -65,11 +65,11 @@ export default class FileSender extends Nanobus {
     this.msg = 'encryptingFile';
     this.emit('encrypting');
 
-    const enc = await this.keychain.encryptStream(this.file);
+    const enc = this.keychain.encryptStream(this.file);
     const metadata = await this.keychain.encryptMetadata(this.file);
     const authKeyB64 = await this.keychain.authKeyB64();
 
-    this.uploadRequest = await uploadWs(
+    this.uploadRequest = uploadWs(
       enc.stream,
       enc.streamInfo,
       metadata,
diff --git a/app/keychain.js b/app/keychain.js
index 89e217e6..75778990 100644
--- a/app/keychain.js
+++ b/app/keychain.js
@@ -179,12 +179,12 @@ export default class Keychain {
     return ciphertext;
   }
 
-  async encryptStream(plaintext) {
+  encryptStream(plaintext) {
     const enc = new ECE(plaintext, this.rawSecret, 'encrypt');
     return enc;
   }
 
-  async decryptStream(encstream) {
+  decryptStream(encstream) {
     const dec = new ECE(encstream, this.rawSecret, 'decrypt');
     return dec;
   }
diff --git a/package-lock.json b/package-lock.json
index 3516b329..6247b8a6 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -4373,16 +4373,6 @@
       "integrity": "sha512-KEyUw8AwRET2iFjFsI1EJQrJ/fHeGiJtgpYgEWG3yDv4l/To/m3a2GaYfeGyB3lsWdvbesjF5XCMx+SVBgAAYw==",
       "requires": {
         "ws": "5.2.0"
-      },
-      "dependencies": {
-        "ws": {
-          "version": "5.2.0",
-          "resolved": "https://registry.npmjs.org/ws/-/ws-5.2.0.tgz",
-          "integrity": "sha512-c18dMeW+PEQdDFzkhDsnBAlS4Z8KGStBQQUcQ5mf7Nf689jyGk0594L+i9RaQuf4gog6SvWLJorz2NfSaqxZ7w==",
-          "requires": {
-            "async-limiter": "1.0.0"
-          }
-        }
       }
     },
     "extend": {
diff --git a/package.json b/package.json
index 66a89781..77e8e22f 100644
--- a/package.json
+++ b/package.json
@@ -132,8 +132,7 @@
     "mozlog": "^2.2.0",
     "raven": "^2.4.2",
     "redis": "^2.8.0",
-    "websocket-stream": "^5.1.2",
-    "ws": "^5.2.0"
+    "websocket-stream": "^5.1.2"
   },
   "availableLanguages": [
     "en-US",
diff --git a/server/routes/ws.js b/server/routes/ws.js
index c29757e1..50ef9055 100644
--- a/server/routes/ws.js
+++ b/server/routes/ws.js
@@ -11,15 +11,13 @@ module.exports = async function(ws, req) {
   let fileStream;
 
   ws.on('close', e => {
-    if (e !== 1000) {
-      if (fileStream !== undefined) {
-        fileStream.destroy();
-      }
+    if (e !== 1000 && fileStream !== undefined) {
+      fileStream.destroy();
     }
   });
 
   let first = true;
-  ws.on('message', function(message) {
+  ws.on('message', async function(message) {
     try {
       if (first) {
         const newId = crypto.randomBytes(5).toString('hex');
@@ -35,6 +33,7 @@ module.exports = async function(ws, req) {
               error: 400
             })
           );
+          ws.close();
         }
 
         const meta = {
@@ -69,6 +68,7 @@ module.exports = async function(ws, req) {
           error: 500
         })
       );
+      ws.close();
     }
   });
 };
diff --git a/test/frontend/tests/api-tests.js b/test/frontend/tests/api-tests.js
index 89b63c1a..1aa5a19f 100644
--- a/test/frontend/tests/api-tests.js
+++ b/test/frontend/tests/api-tests.js
@@ -13,11 +13,11 @@ describe('API', function() {
   describe('websocket upload', function() {
     it('returns file info on success', async function() {
       const keychain = new Keychain();
-      const enc = await keychain.encryptStream(plaintext);
+      const enc = keychain.encryptStream(plaintext);
       const meta = await keychain.encryptMetadata(metadata);
       const verifierB64 = await keychain.authKeyB64();
       const p = function() {};
-      const up = await api.uploadWs(
+      const up = api.uploadWs(
         enc.stream,
         enc.streamInfo,
         meta,
@@ -34,11 +34,11 @@ describe('API', function() {
 
     it('can be cancelled', async function() {
       const keychain = new Keychain();
-      const enc = await keychain.encryptStream(plaintext);
+      const enc = keychain.encryptStream(plaintext);
       const meta = await keychain.encryptMetadata(metadata);
       const verifierB64 = await keychain.authKeyB64();
       const p = function() {};
-      const up = await api.uploadWs(
+      const up = api.uploadWs(
         enc.stream,
         enc.streamInfo,
         meta,