diff --git a/updater_sample/src/com/example/android/systemupdatersample/util/PayloadSpecs.java b/updater_sample/src/com/example/android/systemupdatersample/util/PayloadSpecs.java
index b98b97c..f062317 100644
--- a/updater_sample/src/com/example/android/systemupdatersample/util/PayloadSpecs.java
+++ b/updater_sample/src/com/example/android/systemupdatersample/util/PayloadSpecs.java
@@ -32,7 +32,9 @@
 import java.util.zip.ZipFile;
 
 /** The helper class that creates {@link PayloadSpec}. */
-public final class PayloadSpecs {
+public class PayloadSpecs {
+
+    public PayloadSpecs() {}
 
     /**
      * The payload PAYLOAD_ENTRY is stored in the zip package to comply with the Android OTA package
diff --git a/updater_sample/src/com/example/android/systemupdatersample/util/UpdateEngineErrorCodes.java b/updater_sample/src/com/example/android/systemupdatersample/util/UpdateEngineErrorCodes.java
index 6d319c5..f06ddf7 100644
--- a/updater_sample/src/com/example/android/systemupdatersample/util/UpdateEngineErrorCodes.java
+++ b/updater_sample/src/com/example/android/systemupdatersample/util/UpdateEngineErrorCodes.java
@@ -34,6 +34,7 @@
     * Error code from the update engine. Values must agree with the ones in
     * system/update_engine/common/error_code.h.
     */
+    public static final int UNKNOWN = -1;
     public static final int UPDATED_BUT_NOT_ACTIVE = 52;
 
     private static final SparseArray<String> CODE_TO_NAME_MAP = new SparseArray<>();