diff --git a/lib/modules/database/reference.js b/lib/modules/database/reference.js
index b8025c38..67f88c2d 100644
--- a/lib/modules/database/reference.js
+++ b/lib/modules/database/reference.js
@@ -151,23 +151,25 @@ export default class Reference extends ReferenceBase {
    */
   off(eventName?: string = '', origCB?: () => any) {
     this.log.debug('ref.off(): ', this.refId, eventName);
+    // $FlowFixMe
+    const listeners: Array<DatabaseListener> = Object.values(this.listeners);
     let listenersToRemove;
     if (eventName && origCB) {
-      listenersToRemove = Object.values(this.listeners).filter((listener) => {
+      listenersToRemove = listeners.filter((listener) => {
         return listener.eventName === eventName && listener.successCallback === origCB;
       });
       // Only remove a single listener as per the web spec
       if (listenersToRemove.length > 1) listenersToRemove = [listenersToRemove[0]];
     } else if (eventName) {
-      listenersToRemove = Object.values(this.listeners).filter((listener) => {
+      listenersToRemove = listeners.filter((listener) => {
         return listener.eventName === eventName;
       });
     } else if (origCB) {
-      listenersToRemove = Object.values(this.listeners).filter((listener) => {
+      listenersToRemove = listeners.filter((listener) => {
         return listener.successCallback === origCB;
       });
     } else {
-      listenersToRemove = Object.values(this.listeners);
+      listenersToRemove = listeners;
     }
     // Remove the listeners from the reference to prevent memory leaks
     listenersToRemove.forEach((listener) => {
@@ -183,7 +185,7 @@ export default class Reference extends ReferenceBase {
    * @param onComplete
    * @param applyLocally
    */
-  transaction(transactionUpdate: Function, onComplete, applyLocally: boolean = false) {
+  transaction(transactionUpdate: Function, onComplete: (?Error, boolean, ?Snapshot) => *, applyLocally: boolean = false) {
     if (!isFunction(transactionUpdate)) return Promise.reject(new Error('Missing transactionUpdate function argument.'));
 
     return new Promise((resolve, reject) => {
diff --git a/lib/modules/storage/reference.js b/lib/modules/storage/reference.js
index b8cd4a34..04478d4f 100644
--- a/lib/modules/storage/reference.js
+++ b/lib/modules/storage/reference.js
@@ -80,7 +80,7 @@ export default class StorageReference extends ReferenceBase {
    * Alias to putFile
    * @returns {StorageReference.putFile}
    */
-  get put() {
+  get put(): Function {
     return this.putFile;
   }
 
diff --git a/lib/modules/storage/task.js b/lib/modules/storage/task.js
index 4c8cb638..d365fceb 100644
--- a/lib/modules/storage/task.js
+++ b/lib/modules/storage/task.js
@@ -11,11 +11,13 @@ declare type UploadTaskSnapshotType = {
   downloadURL: string|null,
   metadata: Object, // TODO flow type def for https://firebase.google.com/docs/reference/js/firebase.storage.FullMetadata.html
   ref: StorageReference,
-  state: StorageStatics.TaskState.RUNNING
-    |StorageStatics.TaskState.PAUSED
-    |StorageStatics.TaskState.SUCCESS
-    |StorageStatics.TaskState.CANCELLED
-    |StorageStatics.TaskState.ERROR,
+  state: (
+    typeof StorageStatics.TaskState.RUNNING
+    | typeof StorageStatics.TaskState.PAUSED
+    | typeof StorageStatics.TaskState.SUCCESS
+    | typeof StorageStatics.TaskState.CANCELLED
+    | typeof StorageStatics.TaskState.ERROR
+  ),
   task: StorageTask,
   totalBytes: number,
 };
@@ -32,7 +34,14 @@ declare type NextOrObserverType = null
  * @url https://firebase.google.com/docs/reference/js/firebase.storage.UploadTask
  */
 export default class StorageTask {
-  constructor(type: UPLOAD_TASK|DOWNLOAD_TASK, promise: Promise, storageRef: StorageReference) {
+  type: typeof UPLOAD_TASK | typeof DOWNLOAD_TASK
+  ref: StorageReference
+  storage: StorageReference.storage
+  path: StorageReference.path
+  then: Promise<*>
+  catch: () => Promise<*>
+
+  constructor(type: typeof UPLOAD_TASK | typeof DOWNLOAD_TASK, promise: Promise<*>, storageRef: StorageReference) {
     this.type = type;
     this.ref = storageRef;
     this.storage = storageRef.storage;
@@ -49,13 +58,13 @@ export default class StorageTask {
    * @returns {Promise.<T>}
    * @private
    */
-  _interceptSnapshotEvent(f: Function|null|undefined): null|() => any {
+  _interceptSnapshotEvent(f: ?Function): null | () => * {
     if (!isFunction(f)) return null;
     return (snapshot) => {
       const _snapshot = Object.assign({}, snapshot);
       _snapshot.task = this;
       _snapshot.ref = this.ref;
-      return f(_snapshot);
+      return f && f(_snapshot);
     };
   }
 
@@ -65,12 +74,13 @@ export default class StorageTask {
    * @returns {*}
    * @private
    */
-  _interceptErrorEvent(f: Function|null|undefined): null|() => any {
+  _interceptErrorEvent(f: ?Function): null | (Error) => * {
     if (!isFunction(f)) return null;
     return (error) => {
       const _error = new Error(error.message);
+      // $FlowFixMe
       _error.code = error.code;
-      return f(_error);
+      return f && f(_error);
     };
   }
 
diff --git a/tests/src/containers/CoreContainer.js b/tests/src/containers/CoreContainer.js
index 2111b9dc..82e4452a 100644
--- a/tests/src/containers/CoreContainer.js
+++ b/tests/src/containers/CoreContainer.js
@@ -25,7 +25,7 @@ class CoreContainer extends React.Component {
       StatusBar.setBackgroundColor('#0279ba');
     }
     if (Platform.OS === 'ios') {
-      StatusBar.setBarStyle('light-content')
+      StatusBar.setBarStyle('light-content');
     }
     AppState.addEventListener('change', this.handleAppStateChange);
     NetInfo.isConnected.fetch().then((isConnected) => {
@@ -44,6 +44,7 @@ class CoreContainer extends React.Component {
   }
 
   props: Props;
+  _isConnected: boolean;
 
   /**
    * Handle app state changes