diff --git a/core/java/android/os/image/DynamicSystemClient.java b/core/java/android/os/image/DynamicSystemClient.java
index 5cb33615fe22e..50d8d8079ed59 100644
--- a/core/java/android/os/image/DynamicSystemClient.java
+++ b/core/java/android/os/image/DynamicSystemClient.java
@@ -96,9 +96,6 @@ public class DynamicSystemClient {
 
     private static final String TAG = "DynSystemClient";
 
-    private static final long DEFAULT_USERDATA_SIZE = (10L << 30);
-
-
     /** Listener for installation status updates. */
     public interface OnStatusChangedListener {
         /**
@@ -386,7 +383,7 @@ public class DynamicSystemClient {
     @SystemApi
     @TestApi
     public void start(@NonNull Uri systemUrl, @BytesLong long systemSize) {
-        start(systemUrl, systemSize, DEFAULT_USERDATA_SIZE);
+        start(systemUrl, systemSize, 0 /* Use the default userdata size */);
     }
 
     /**
diff --git a/packages/DynamicSystemInstallationService/src/com/android/dynsystem/DynamicSystemInstallationService.java b/packages/DynamicSystemInstallationService/src/com/android/dynsystem/DynamicSystemInstallationService.java
index 37a77be529838..f36f97ddf6109 100644
--- a/packages/DynamicSystemInstallationService/src/com/android/dynsystem/DynamicSystemInstallationService.java
+++ b/packages/DynamicSystemInstallationService/src/com/android/dynsystem/DynamicSystemInstallationService.java
@@ -82,6 +82,9 @@ public class DynamicSystemInstallationService extends Service
     static final String DEFAULT_DSU_SLOT = "dsu";
     static final String KEY_PUBKEY = "KEY_PUBKEY";
 
+    // Default userdata partition size is 2GiB.
+    private static final long DEFAULT_USERDATA_SIZE = 2L << 30;
+
     /*
      * Intent actions
      */
@@ -270,6 +273,10 @@ public class DynamicSystemInstallationService extends Service
         String dsuSlot = intent.getStringExtra(KEY_DSU_SLOT);
         String publicKey = intent.getStringExtra(KEY_PUBKEY);
 
+        if (userdataSize == 0) {
+            userdataSize = DEFAULT_USERDATA_SIZE;
+        }
+
         if (TextUtils.isEmpty(dsuSlot)) {
             dsuSlot = DEFAULT_DSU_SLOT;
         }