diff --git a/services/core/java/com/android/server/accounts/AccountManagerService.java b/services/core/java/com/android/server/accounts/AccountManagerService.java
index 6b731c3..8dc02c1 100644
--- a/services/core/java/com/android/server/accounts/AccountManagerService.java
+++ b/services/core/java/com/android/server/accounts/AccountManagerService.java
@@ -4794,6 +4794,7 @@
 
     private abstract class Session extends IAccountAuthenticatorResponse.Stub
             implements IBinder.DeathRecipient, ServiceConnection {
+        private final Object mSessionLock = new Object();
         IAccountManagerResponse mResponse;
         final String mAccountType;
         final boolean mExpectActivityLaunch;
@@ -4959,9 +4960,11 @@
         }
 
         private void unbind() {
-            if (mAuthenticator != null) {
-                mAuthenticator = null;
-                mContext.unbindService(this);
+            synchronized (mSessionLock) {
+                if (mAuthenticator != null) {
+                    mAuthenticator = null;
+                    mContext.unbindService(this);
+                }
             }
         }
 
@@ -4971,12 +4974,14 @@
 
         @Override
         public void onServiceConnected(ComponentName name, IBinder service) {
-            mAuthenticator = IAccountAuthenticator.Stub.asInterface(service);
-            try {
-                run();
-            } catch (RemoteException e) {
-                onError(AccountManager.ERROR_CODE_REMOTE_EXCEPTION,
-                        "remote exception");
+            synchronized (mSessionLock) {
+                mAuthenticator = IAccountAuthenticator.Stub.asInterface(service);
+                try {
+                    run();
+                } catch (RemoteException e) {
+                    onError(AccountManager.ERROR_CODE_REMOTE_EXCEPTION,
+                            "remote exception");
+                }
             }
         }