diff --git a/packages/shared_preferences/CHANGELOG.md b/packages/shared_preferences/CHANGELOG.md
index 9015bd836daa..5560dd8a4317 100644
--- a/packages/shared_preferences/CHANGELOG.md
+++ b/packages/shared_preferences/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.5.4+4
+
+* `setMockInitialValues` needs to handle non-prefixed keys since that's an implementation detail.
+
 ## 0.5.4+3
 
 * Android: Suppress casting warnings.
diff --git a/packages/shared_preferences/README.md b/packages/shared_preferences/README.md
index 136c6de3dd99..dfd449337293 100644
--- a/packages/shared_preferences/README.md
+++ b/packages/shared_preferences/README.md
@@ -42,11 +42,5 @@ _incrementCounter() async {
 You can populate `SharedPreferences` with initial values in your tests by running this code:
 
 ```dart
-const MethodChannel('plugins.flutter.io/shared_preferences')
-  .setMockMethodCallHandler((MethodCall methodCall) async {
-    if (methodCall.method == 'getAll') {
-      return <String, dynamic>{}; // set initial values here if desired
-    }
-    return null;
-  });
+SharedPrefernces.setMockInitialValues (Map<String, dynamic> values);
 ```
diff --git a/packages/shared_preferences/lib/shared_preferences.dart b/packages/shared_preferences/lib/shared_preferences.dart
index aece19b6e29e..3fe176f41f25 100644
--- a/packages/shared_preferences/lib/shared_preferences.dart
+++ b/packages/shared_preferences/lib/shared_preferences.dart
@@ -181,9 +181,17 @@ class SharedPreferences {
   /// If the singleton instance has been initialized already, it is nullified.
   @visibleForTesting
   static void setMockInitialValues(Map<String, dynamic> values) {
+    final Map<String, dynamic> newValues =
+        values.map<String, dynamic>((String key, dynamic value) {
+      String newKey = key;
+      if (!key.startsWith(_prefix)) {
+        newKey = '$_prefix$key';
+      }
+      return MapEntry<String, dynamic>(newKey, value);
+    });
     _kChannel.setMockMethodCallHandler((MethodCall methodCall) async {
       if (methodCall.method == 'getAll') {
-        return values;
+        return newValues;
       }
       return null;
     });
diff --git a/packages/shared_preferences/pubspec.yaml b/packages/shared_preferences/pubspec.yaml
index 9df0c19f1a3a..80bfc6d219e3 100644
--- a/packages/shared_preferences/pubspec.yaml
+++ b/packages/shared_preferences/pubspec.yaml
@@ -3,7 +3,7 @@ description: Flutter plugin for reading and writing simple key-value pairs.
   Wraps NSUserDefaults on iOS and SharedPreferences on Android.
 author: Flutter Team <flutter-dev@googlegroups.com>
 homepage: https://github.com/flutter/plugins/tree/master/packages/shared_preferences
-version: 0.5.4+3
+version: 0.5.4+4
 
 flutter:
   plugin:
diff --git a/packages/shared_preferences/test/shared_preferences_test.dart b/packages/shared_preferences/test/shared_preferences_test.dart
index 8ebcb96c0ad8..d171f7ae7f05 100755
--- a/packages/shared_preferences/test/shared_preferences_test.dart
+++ b/packages/shared_preferences/test/shared_preferences_test.dart
@@ -197,4 +197,13 @@ void main() {
       expect(preferences.getStringList('myList'), <String>[]);
     });
   });
+
+  test('calling mock initial values with non-prefixed keys succeeds', () async {
+    SharedPreferences.setMockInitialValues(<String, String>{
+      'test': 'foo',
+    });
+    final SharedPreferences prefs = await SharedPreferences.getInstance();
+    final String value = prefs.getString('test');
+    expect(value, 'foo');
+  });
 }