diff --git a/src/views/CardStackStyleInterpolator.js b/src/views/CardStackStyleInterpolator.js
index 7e4c9ba..4892124 100644
--- a/src/views/CardStackStyleInterpolator.js
+++ b/src/views/CardStackStyleInterpolator.js
@@ -1,6 +1,6 @@
 /* @flow */
 
-import { I18nManager } from 'react-native';
+import { I18nManager, type AnimatedViewStylePropTypes } from 'react-native';
 
 import type { NavigationSceneRendererProps } from '../TypeDefinition';
 
@@ -22,7 +22,9 @@ import type { NavigationSceneRendererProps } from '../TypeDefinition';
 /**
  * Render the initial style when the initial layout isn't measured yet.
  */
-function forInitial(props: NavigationSceneRendererProps): Object {
+function forInitial(
+  props: NavigationSceneRendererProps
+): AnimatedViewStylePropTypes {
   const { navigation, scene } = props;
 
   const focused = navigation.state.index === scene.index;
@@ -38,7 +40,9 @@ function forInitial(props: NavigationSceneRendererProps): Object {
 /**
  * Standard iOS-style slide in from the right.
  */
-function forHorizontal(props: NavigationSceneRendererProps): Object {
+function forHorizontal(
+  props: NavigationSceneRendererProps
+): AnimatedViewStylePropTypes {
   const { layout, position, scene } = props;
 
   if (!layout.isMeasured) {
@@ -81,7 +85,9 @@ function forHorizontal(props: NavigationSceneRendererProps): Object {
 /**
  * Standard iOS-style slide in from the bottom (used for modals).
  */
-function forVertical(props: NavigationSceneRendererProps): Object {
+function forVertical(
+  props: NavigationSceneRendererProps
+): AnimatedViewStylePropTypes {
   const { layout, position, scene } = props;
 
   if (!layout.isMeasured) {
@@ -117,7 +123,9 @@ function forVertical(props: NavigationSceneRendererProps): Object {
 /**
  * Standard Android-style fade in from the bottom.
  */
-function forFadeFromBottomAndroid(props: NavigationSceneRendererProps): Object {
+function forFadeFromBottomAndroid(
+  props: NavigationSceneRendererProps
+): AnimatedViewStylePropTypes {
   const { layout, position, scene } = props;
 
   if (!layout.isMeasured) {