diff --git a/src/base-apis.js b/src/base-apis.js
index 9186c3f25..8018881fc 100644
--- a/src/base-apis.js
+++ b/src/base-apis.js
@@ -1596,7 +1596,8 @@ MatrixBaseApis.prototype.uploadKeysRequest = function(content, opts, callback) {
 
 MatrixBaseApis.prototype.uploadKeySignatures = function(content) {
     return this._http.authedRequestWithPrefix(
-        undefined, "POST", '/keys/signatures/upload', undefined, content, httpApi.PREFIX_UNSTABLE,
+        undefined, "POST", '/keys/signatures/upload', undefined,
+        content, httpApi.PREFIX_UNSTABLE,
     );
 };
 
diff --git a/src/client.js b/src/client.js
index c3e81aa11..cb24c3894 100644
--- a/src/client.js
+++ b/src/client.js
@@ -958,7 +958,9 @@ MatrixClient.prototype.prepareKeyBackupVersion = async function(password) {
         throw new Error("End-to-end encryption disabled");
     }
 
-    let decryption, encryption, signing;
+    let decryption;
+    let encryption;
+    let signing;
     try {
         decryption = new global.Olm.PkDecryption();
         encryption = new global.Olm.PkEncryption();
@@ -988,32 +990,43 @@ MatrixClient.prototype.prepareKeyBackupVersion = async function(password) {
         };
 
         if (signing) {
-            await this._cryptoStore.doTxn('readonly', [IndexedDBCryptoStore.STORE_ACCOUNT], (txn) => {
-                this._cryptoStore.getAccountKeys(txn, keys => {
-                    returnInfo.accountKeys = keys;
-                });
-            });
+            await this._cryptoStore.doTxn(
+                'readonly', [IndexedDBCryptoStore.STORE_ACCOUNT],
+                (txn) => {
+                    this._cryptoStore.getAccountKeys(txn, (keys) => {
+                        returnInfo.accountKeys = keys;
+                    });
+                },
+            );
 
             if (!returnInfo.accountKeys) {
-                const ssk_seed = signing.generate_seed();
-                const usk_seed = signing.generate_seed();
+                const sskSeed = signing.generate_seed();
+                const uskSeed = signing.generate_seed();
 
                 returnInfo.accountKeys = {
-                    self_signing_key_seed: Buffer.from(ssk_seed).toString('base64'),
-                    user_signing_key_seed: Buffer.from(usk_seed).toString('base64'),
-                }
+                    self_signing_key_seed: Buffer.from(sskSeed).toString('base64'),
+                    user_signing_key_seed: Buffer.from(uskSeed).toString('base64'),
+                };
             }
 
             // put the encrypted version of the seed in the auth data to upload
             // XXX: our encryption really should support encrypting binary data.
-            authData.self_signing_key_seed = encryption.encrypt(returnInfo.accountKeys.self_signing_key_seed);
+            authData.self_signing_key_seed = encryption.encrypt(
+                returnInfo.accountKeys.self_signing_key_seed,
+            );
             // also keep the public part there
-            returnInfo.ssk_public = signing.init_with_seed(Buffer.from(returnInfo.accountKeys.self_signing_key_seed, 'base64'));
+            returnInfo.ssk_public = signing.init_with_seed(
+                Buffer.from(returnInfo.accountKeys.self_signing_key_seed, 'base64'),
+            );
             signing.free();
 
             // same for the USK
-            authData.user_signing_key_seed = encryption.encrypt(returnInfo.accountKeys.user_signing_key_seed);
-            returnInfo.usk_public = signing.init_with_seed(Buffer.from(returnInfo.accountKeys.user_signing_key_seed, 'base64'));
+            authData.user_signing_key_seed = encryption.encrypt(
+                returnInfo.accountKeys.user_signing_key_seed,
+            );
+            returnInfo.usk_public = signing.init_with_seed(
+                Buffer.from(returnInfo.accountKeys.user_signing_key_seed, 'base64'),
+            );
             signing.free();
 
             // we don't save these keys back to the store yet: we'll do that when (if) we
@@ -1033,6 +1046,8 @@ MatrixClient.prototype.prepareKeyBackupVersion = async function(password) {
  * from prepareKeyBackupVersion.
  *
  * @param {object} info Info object from prepareKeyBackupVersion
+ * @param {object} auth Auth object for UI auth
+ * @param {string} replacesSsk If the SSK is being replaced, the ID of the old key
  * @returns {Promise<object>} Object with 'version' param indicating the version created
  */
 MatrixClient.prototype.createKeyBackupVersion = async function(info, auth, replacesSsk) {
@@ -1054,7 +1069,11 @@ MatrixClient.prototype.createKeyBackupVersion = async function(info, auth, repla
     };
 
     // sign the USK with the SSK
-    pkSign(uskInfo, Buffer.from(info.accountKeys.self_signing_key_seed, 'base64'), this.credentials.userId);
+    pkSign(
+        uskInfo,
+        Buffer.from(info.accountKeys.self_signing_key_seed, 'base64'),
+        this.credentials.userId,
+    );
 
     // Now sig the backup auth data. Do it as this device first because crypto._signObject
     // is dumb and bluntly replaces the whole signatures block...
@@ -1062,7 +1081,11 @@ MatrixClient.prototype.createKeyBackupVersion = async function(info, auth, repla
     await this._crypto._signObject(data.auth_data);
 
     // now also sign the auth data with the SSK
-    pkSign(data.auth_data, Buffer.from(info.accountKeys.self_signing_key_seed, 'base64'), this.credentials.userId);
+    pkSign(
+        data.auth_data,
+        Buffer.from(info.accountKeys.self_signing_key_seed, 'base64'),
+        this.credentials.userId,
+    );
 
     const keys = {
         self_signing_key: {
@@ -1077,10 +1100,13 @@ MatrixClient.prototype.createKeyBackupVersion = async function(info, auth, repla
         auth,
     };
 
-    return this._cryptoStore.doTxn('readwrite', [IndexedDBCryptoStore.STORE_ACCOUNT], (txn) => {
-        // store the newly generated account keys
-        this._cryptoStore.storeAccountKeys(txn, info.accountKeys);
-    }).then(() => {
+    return this._cryptoStore.doTxn(
+        'readwrite', [IndexedDBCryptoStore.STORE_ACCOUNT],
+        (txn) => {
+            // store the newly generated account keys
+            this._cryptoStore.storeAccountKeys(txn, info.accountKeys);
+        },
+    ).then(() => {
         // re-check the SSK in the device store if necessary
         return this._crypto.checkOwnSskTrust();
     }).then(() => {
@@ -1220,11 +1246,14 @@ MatrixClient.prototype._restoreKeyBackup = async function(
         // decrypt the account keys from the backup info if there are any
         // fetch the old ones first so we don't lose info if only one of them is in the backup
         let accountKeys;
-        await this._cryptoStore.doTxn('readonly', [IndexedDBCryptoStore.STORE_ACCOUNT], (txn) => {
-            this._cryptoStore.getAccountKeys(txn, keys => {
-                accountKeys = keys || {};
-            });
-        });
+        await this._cryptoStore.doTxn(
+            'readonly', [IndexedDBCryptoStore.STORE_ACCOUNT],
+            (txn) => {
+                this._cryptoStore.getAccountKeys(txn, (keys) => {
+                    accountKeys = keys || {};
+                });
+            },
+        );
 
         if (backupInfo.auth_data.self_signing_key_seed) {
             accountKeys.self_signing_key_seed = decryption.decrypt(
@@ -1241,9 +1270,12 @@ MatrixClient.prototype._restoreKeyBackup = async function(
             );
         }
 
-        await this._cryptoStore.doTxn('readwrite', [IndexedDBCryptoStore.STORE_ACCOUNT], (txn) => {
-            this._cryptoStore.storeAccountKeys(txn, accountKeys);
-        });
+        await this._cryptoStore.doTxn(
+            'readwrite', [IndexedDBCryptoStore.STORE_ACCOUNT],
+            (txn) => {
+                this._cryptoStore.storeAccountKeys(txn, accountKeys);
+            },
+        );
 
         await this._crypto.checkOwnSskTrust();
     } catch(e) {
@@ -1254,7 +1286,9 @@ MatrixClient.prototype._restoreKeyBackup = async function(
     // start by signing this device from the SSK now we have it
     return this._crypto.uploadDeviceKeySignatures().then(() => {
         // Now fetch the encrypted keys
-        const path = this._makeKeyBackupPath(targetRoomId, targetSessionId, backupInfo.version);
+        const path = this._makeKeyBackupPath(
+            targetRoomId, targetSessionId, backupInfo.version,
+        );
         return this._http.authedRequest(
             undefined, "GET", path.path, path.queryData,
         );
diff --git a/src/crypto/DeviceList.js b/src/crypto/DeviceList.js
index 6ff51789c..16b59bd1c 100644
--- a/src/crypto/DeviceList.js
+++ b/src/crypto/DeviceList.js
@@ -788,7 +788,9 @@ class DeviceListUpdateSerialiser {
             let prom = Promise.resolve();
             for (const userId of downloadUsers) {
                 prom = prom.delay(5).then(() => {
-                    return this._processQueryResponseForUser(userId, dk[userId], ssks[userId]);
+                    return this._processQueryResponseForUser(
+                        userId, dk[userId], ssks[userId],
+                    );
                 });
             }
 
@@ -812,9 +814,9 @@ class DeviceListUpdateSerialiser {
         return deferred.promise;
     }
 
-    async _processQueryResponseForUser(userId, dk_response, ssk_response) {
-        logger.log('got device keys for ' + userId + ':', dk_response);
-        logger.log('got self-signing keys for ' + userId + ':', ssk_response);
+    async _processQueryResponseForUser(userId, dkResponse, sskResponse) {
+        logger.log('got device keys for ' + userId + ':', dkResponse);
+        logger.log('got self-signing keys for ' + userId + ':', sskResponse);
 
         {
             // map from deviceid -> deviceinfo for this user
@@ -828,7 +830,7 @@ class DeviceListUpdateSerialiser {
             }
 
             await _updateStoredDeviceKeysForUser(
-                this._olmDevice, userId, userStore, dk_response || {},
+                this._olmDevice, userId, userStore, dkResponse || {},
             );
 
             // put the updates into the object that will be returned as our results
@@ -845,7 +847,7 @@ class DeviceListUpdateSerialiser {
             const ssk = this._deviceList.getRawStoredSskForUser(userId) || {};
 
             const updated = await _updateStoredSelfSigningKeyForUser(
-                this._olmDevice, userId, ssk, ssk_response || {},
+                this._olmDevice, userId, ssk, sskResponse || {},
             );
 
             this._deviceList.setRawStoredSskForUser(userId, ssk);
diff --git a/src/crypto/PkSigning.js b/src/crypto/PkSigning.js
index 4de1c2f3e..483b13437 100644
--- a/src/crypto/PkSigning.js
+++ b/src/crypto/PkSigning.js
@@ -18,6 +18,9 @@ const anotherjson = require('another-json');
 
 /**
  * Higher level wrapper around olm.PkSigning that signs JSON objects
+ * @param obj {Object} Object to sign
+ * @param seed {Uint8Array} The private key seed (32 bytes)
+ * @param userId {string} The user ID who owns the signing key
  */
 export function pkSign(obj, seed, userId) {
     const signing = new global.Olm.PkSigning();
diff --git a/src/crypto/index.js b/src/crypto/index.js
index 5162a892c..e60374846 100644
--- a/src/crypto/index.js
+++ b/src/crypto/index.js
@@ -268,7 +268,7 @@ Crypto.prototype._onDeviceListUserSskUpdated = async function(userId) {
     if (userId === this._userId) {
         this.checkOwnSskTrust();
     }
-}
+};
 
 /*
  * Check the copy of our SSK that we have in the device list and see if it
@@ -303,7 +303,7 @@ Crypto.prototype.checkOwnSskTrust = async function() {
     let localPubkey;
     try {
         signing = new global.Olm.PkSigning();
-        localPubkey = signing.init_with_seed(Buffer.from(accountKeys.self_signing_key_seed, 'base64'))
+        localPubkey = signing.init_with_seed(Buffer.from(accountKeys.self_signing_key_seed, 'base64'));
     } finally {
         if (signing) signing.free();
         signing = null;
@@ -467,7 +467,7 @@ Crypto.prototype.isKeyBackupTrusted = async function(backupInfo) {
             s.valid && (
                 (s.device && s.device.isVerified()) || (s.self_signing_key && s.self_signing_key.isVerified())
             )
-        )
+        );
     });
     return ret;
 };
@@ -622,7 +622,7 @@ Crypto.prototype.uploadDeviceKeySignatures = async function() {
     };
 
     await crypto._baseApis.uploadKeySignatures(content);
-    return true
+    return true;
 };
 
 /**
@@ -829,7 +829,7 @@ Crypto.prototype.setSskVerification = async function(userId, verified) {
         throw new Error("No self-signing key found for user " + userId);
     }
     ssk.verified = verified;
-    this._deviceList.storeSskForUser(userId, ssk)
+    this._deviceList.storeSskForUser(userId, ssk);
     this._deviceList.saveIfDirty();
 };