diff --git a/src/api.coffee b/src/api.coffee
index 56aaa711..ba7910ab 100644
--- a/src/api.coffee
+++ b/src/api.coffee
@@ -67,20 +67,20 @@ module.exports = (secret) ->
 		utils.mixpanelTrack('Purge /data', appId)
 		if !appId?
 			return res.status(400).send('Missing app id')
-		knex('app').select().where({ appId })
-		.then ([ app ]) ->
-			if !app?
-				throw new Error('App not found')
-			Promise.using application.lockUpdates(app), ->
+		Promise.using application.lockUpdates(app), ->
+			knex('app').select().where({ appId })
+			.then ([ app ]) ->
+				if !app?
+					throw new Error('App not found')
 				application.kill(app)
-				.then ->
-					new Promise (resolve, reject) ->
-						request.post(config.gosuperAddress + '/v1/purge', { json: true, body: applicationId: appId.toString() })
-						.on 'error', reject
-						.on 'response', -> resolve()
-						.pipe(res)
-					.finally ->
-						application.start(app)
+			.then ->
+				new Promise (resolve, reject) ->
+					request.post(config.gosuperAddress + '/v1/purge', { json: true, body: applicationId: appId.toString() })
+					.on 'error', reject
+					.on 'response', -> resolve()
+					.pipe(res)
+				.finally ->
+					application.start(app)
 		.catch (err) ->
 			res.status(503).send(err?.message or err or 'Unknown error')
 
diff --git a/src/application.coffee b/src/application.coffee
index 6a63c1a7..6bf59069 100644
--- a/src/application.coffee
+++ b/src/application.coffee
@@ -251,13 +251,19 @@ exports.unlockAndStart = unlockAndStart = (app) ->
 	.then ->
 		start(app)
 
-exports.lockUpdates = lockUpdates = (app, force) ->
-	Promise.try ->
-		lockFile.unlockAsync(lockPath(app)) if force == true
-	.then ->
-		lockFile.lockAsync(lockPath(app))
-	.disposer ->
-		lockFile.unlockAsync(lockPath(app))
+exports.lockUpdates = lockUpdates = do ->
+	_lock = new Lock()
+	_writeLock = Promise.promisify(_lock.async.writeLock)
+	return (app, force) ->
+		_writeLock(lockPath(app))
+		.tap ->
+			lockFile.unlockAsync(lockPath(app)) if force == true
+		.tap ->
+			lockFile.lockAsync(lockPath(app))
+		.disposer (release) ->
+			lockFile.unlockAsync(lockPath(app))
+			.then ->
+				release()
 
 joinErrorMessages = (failures) ->
 	s = if failures.length > 1 then 's' else ''
@@ -354,7 +360,13 @@ exports.update = update = (force) ->
 				# Then delete all the ones to remove in one go
 				Promise.map toBeRemoved, (appId) ->
 					Promise.using lockUpdates(apps[appId], force), ->
-						kill(apps[appId])
+						# We get the app from the DB again in case someone restarted it
+						# (which would have changed its containerId)
+						knex('app').select().where({ appId })
+						.then ([ app ]) ->
+							if !app?
+								throw new Error('App not found')
+							kill(app)
 						.then ->
 							knex('app').where('appId', appId).delete()
 					.catch (err) ->
@@ -372,7 +384,11 @@ exports.update = update = (force) ->
 						app = remoteApps[appId]
 						logSystemEvent(logTypes.updateApp, app) if localApp.imageId == app.imageId
 						Promise.using lockUpdates(localApp, force), ->
-							kill(localApp)
+							knex('app').select().where({ appId })
+							.then ([ localApp ]) ->
+								if !localApp?
+									throw new Error('App not found')
+								kill(localApp)
 							.then ->
 								start(app)
 						.catch (err) ->