diff --git a/core/java/android/os/BaseBundle.java b/core/java/android/os/BaseBundle.java
index c3733085caf63..532070e36998e 100644
--- a/core/java/android/os/BaseBundle.java
+++ b/core/java/android/os/BaseBundle.java
@@ -31,7 +31,9 @@ public class BaseBundle {
     private static final String TAG = "Bundle";
     static final boolean DEBUG = false;
 
+    // Keep in sync with frameworks/native/libs/binder/PersistableBundle.cpp.
     static final int BUNDLE_MAGIC = 0x4C444E42; // 'B' 'N' 'D' 'L'
+
     static final Parcel EMPTY_PARCEL;
 
     static {
@@ -1307,6 +1309,8 @@ public class BaseBundle {
      * @param parcel The parcel to copy this bundle to.
      */
     void writeToParcelInner(Parcel parcel, int flags) {
+        // Keep implementation in sync with writeToParcel() in
+        // frameworks/native/libs/binder/PersistableBundle.cpp.
         if (mParcelledData != null) {
             if (mParcelledData == EMPTY_PARCEL) {
                 parcel.writeInt(0);
@@ -1344,6 +1348,8 @@ public class BaseBundle {
      * @param parcel The parcel to overwrite this bundle from.
      */
     void readFromParcelInner(Parcel parcel) {
+        // Keep implementation in sync with readFromParcel() in
+        // frameworks/native/libs/binder/PersistableBundle.cpp.
         int length = parcel.readInt();
         if (length < 0) {
             throw new RuntimeException("Bad length in parcel: " + length);
diff --git a/core/java/android/os/Parcel.java b/core/java/android/os/Parcel.java
index 290202194732b..26312475297c3 100644
--- a/core/java/android/os/Parcel.java
+++ b/core/java/android/os/Parcel.java
@@ -204,6 +204,7 @@ public final class Parcel {
     private static final Parcel[] sOwnedPool = new Parcel[POOL_SIZE];
     private static final Parcel[] sHolderPool = new Parcel[POOL_SIZE];
 
+    // Keep in sync with frameworks/native/libs/binder/PersistableBundle.cpp.
     private static final int VAL_NULL = -1;
     private static final int VAL_STRING = 0;
     private static final int VAL_INTEGER = 1;
@@ -704,6 +705,8 @@ public final class Parcel {
             writeInt(-1);
             return;
         }
+        // Keep the format of this Parcel in sync with writeToParcelInner() in
+        // frameworks/native/libs/binder/PersistableBundle.cpp.
         final int N = val.size();
         writeInt(N);
         if (DEBUG_ARRAY_MAP) {