diff --git a/Libraries/BatchedBridge/BatchedBridgedModules/NativeModules.js b/Libraries/BatchedBridge/BatchedBridgedModules/NativeModules.js
index d0ae13c26..e3a179887 100644
--- a/Libraries/BatchedBridge/BatchedBridgedModules/NativeModules.js
+++ b/Libraries/BatchedBridge/BatchedBridgedModules/NativeModules.js
@@ -7,6 +7,7 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *
  * @providesModule NativeModules
+ * @flow
  */
 'use strict';
 
diff --git a/Libraries/BatchedBridge/BatchedBridgedModules/RCTAlertManager.ios.js b/Libraries/BatchedBridge/BatchedBridgedModules/RCTAlertManager.ios.js
index ddd1cc36c..409ecf5ca 100644
--- a/Libraries/BatchedBridge/BatchedBridgedModules/RCTAlertManager.ios.js
+++ b/Libraries/BatchedBridge/BatchedBridgedModules/RCTAlertManager.ios.js
@@ -7,6 +7,7 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *
  * @providesModule RCTAlertManager
+ * @flow
  */
 'use strict';
 
diff --git a/Libraries/BatchedBridge/BatchedBridgedModules/RCTEventEmitter.js b/Libraries/BatchedBridge/BatchedBridgedModules/RCTEventEmitter.js
index 5ac00588e..7f875946e 100644
--- a/Libraries/BatchedBridge/BatchedBridgedModules/RCTEventEmitter.js
+++ b/Libraries/BatchedBridge/BatchedBridgedModules/RCTEventEmitter.js
@@ -7,6 +7,7 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *
  * @providesModule RCTEventEmitter
+ * @flow
  */
 'use strict';
 
diff --git a/Libraries/BatchedBridge/BatchedBridgedModules/RCTJSTimers.js b/Libraries/BatchedBridge/BatchedBridgedModules/RCTJSTimers.js
index 595cdce57..08a126b00 100644
--- a/Libraries/BatchedBridge/BatchedBridgedModules/RCTJSTimers.js
+++ b/Libraries/BatchedBridge/BatchedBridgedModules/RCTJSTimers.js
@@ -7,6 +7,7 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *
  * @providesModule RCTJSTimers
+ * @flow
  */
 'use strict';
 
diff --git a/Libraries/CameraRoll/CameraRoll.js b/Libraries/CameraRoll/CameraRoll.js
index db74c4619..6acc949e5 100644
--- a/Libraries/CameraRoll/CameraRoll.js
+++ b/Libraries/CameraRoll/CameraRoll.js
@@ -7,6 +7,7 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *
  * @providesModule CameraRoll
+ * @flow
  */
 'use strict';
 
@@ -28,7 +29,8 @@ var GROUP_TYPES_OPTIONS = [
   'SavedPhotos', // default
 ];
 
-deepFreezeAndThrowOnMutationInDev(GROUP_TYPES_OPTIONS);
+// Flow treats Object and Array as disjoint types, currently.
+deepFreezeAndThrowOnMutationInDev((GROUP_TYPES_OPTIONS: any));
 
 /**
  * Shape of the param arg for the `getPhotos` function.
diff --git a/Libraries/Device/RCTDeviceEventEmitter.js b/Libraries/Device/RCTDeviceEventEmitter.js
index dce621933..586663e34 100644
--- a/Libraries/Device/RCTDeviceEventEmitter.js
+++ b/Libraries/Device/RCTDeviceEventEmitter.js
@@ -7,6 +7,7 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *
  * @providesModule RCTDeviceEventEmitter
+ * @flow
  */
 'use strict';
 
diff --git a/Libraries/Geolocation/Geolocation.ios.js b/Libraries/Geolocation/Geolocation.ios.js
index 4aae5ece8..eb33fbbbe 100644
--- a/Libraries/Geolocation/Geolocation.ios.js
+++ b/Libraries/Geolocation/Geolocation.ios.js
@@ -7,6 +7,7 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *
  * @providesModule Geolocation
+ * @flow
  */
 'use strict';
 
@@ -33,7 +34,10 @@ var updatesEnabled = false;
  */
 var Geolocation = {
 
-  getCurrentPosition: function(geo_success, geo_error, geo_options) {
+  getCurrentPosition: function(
+    geo_success: Function,
+    geo_error?: Function,
+    geo_options?: Object) {
     invariant(
       typeof geo_success === 'function',
       'Must provide a valid geo_success callback.'
@@ -45,7 +49,7 @@ var Geolocation = {
     );
   },
 
-  watchPosition: function(success, error, options) {
+  watchPosition: function(success: Function, error?: Function, options?: Object): number {
     if (!updatesEnabled) {
       RCTLocationObserver.startObserving(options || {});
       updatesEnabled = true;
@@ -64,15 +68,17 @@ var Geolocation = {
     return watchID;
   },
 
-  clearWatch: function(watchID) {
+  clearWatch: function(watchID: number) {
     var sub = subscriptions[watchID];
     if (!sub) {
       // Silently exit when the watchID is invalid or already cleared
       // This is consistent with timers
       return;
     }
+
     sub[0].remove();
-    sub[1] && sub[1].remove();
+    // array element refinements not yet enabled in Flow
+    var sub1 = sub[1]; sub1 && sub1.remove();
     subscriptions[watchID] = undefined;
     var noWatchers = true;
     for (var ii = 0; ii < subscriptions.length; ii++) {
@@ -90,9 +96,12 @@ var Geolocation = {
       RCTLocationObserver.stopObserving();
       updatesEnabled = false;
       for (var ii = 0; ii < subscriptions.length; ii++) {
-        if (subscriptions[ii]) {
+        var sub = subscriptions[ii];
+        if (sub) {
           warning('Called stopObserving with existing subscriptions.');
-          subscriptions[ii].remove();
+          sub[0].remove();
+          // array element refinements not yet enabled in Flow
+          var sub1 = sub[1]; sub1 && sub1.remove();
         }
       }
       subscriptions = [];