diff --git a/services/core/java/com/android/server/wm/DisplayContent.java b/services/core/java/com/android/server/wm/DisplayContent.java
index 92d26cb..e0e4477 100644
--- a/services/core/java/com/android/server/wm/DisplayContent.java
+++ b/services/core/java/com/android/server/wm/DisplayContent.java
@@ -759,16 +759,25 @@
         return token.asAppWindowToken();
     }
 
-    void addWindowToken(IBinder binder, WindowToken token) {
+    private void addWindowToken(IBinder binder, WindowToken token) {
         final DisplayContent dc = mService.mRoot.getWindowTokenDisplay(token);
         if (dc != null) {
             // We currently don't support adding a window token to the display if the display
             // already has the binder mapped to another token. If there is a use case for supporting
             // this moving forward we will either need to merge the WindowTokens some how or have
             // the binder map to a list of window tokens.
-            throw new IllegalArgumentException("Can't map token=" + token + " to display=" + this
-                    + " already mapped to display=" + dc + " tokens=" + dc.mTokenMap);
+            throw new IllegalArgumentException("Can't map token=" + token + " to display="
+                    + getName() + " already mapped to display=" + dc + " tokens=" + dc.mTokenMap);
         }
+        if (binder == null) {
+            throw new IllegalArgumentException("Can't map token=" + token + " to display="
+                    + getName() + " binder is null");
+        }
+        if (token == null) {
+            throw new IllegalArgumentException("Can't map null token to display="
+                    + getName() + " binder=" + binder);
+        }
+
         mTokenMap.put(binder, token);
 
         if (token.asAppWindowToken() == null) {
diff --git a/services/core/java/com/android/server/wm/WindowManagerService.java b/services/core/java/com/android/server/wm/WindowManagerService.java
index a48397b..fac5c02 100644
--- a/services/core/java/com/android/server/wm/WindowManagerService.java
+++ b/services/core/java/com/android/server/wm/WindowManagerService.java
@@ -1239,7 +1239,8 @@
                         return WindowManagerGlobal.ADD_BAD_APP_TOKEN;
                     }
                 }
-                token = new WindowToken(this, attrs.token, type, false, displayContent,
+                final IBinder binder = attrs.token != null ? attrs.token : client.asBinder();
+                token = new WindowToken(this, binder, type, false, displayContent,
                         session.mCanAddInternalSystemWindow);
             } else if (rootType >= FIRST_APPLICATION_WINDOW && rootType <= LAST_APPLICATION_WINDOW) {
                 atoken = token.asAppWindowToken();
@@ -1310,7 +1311,7 @@
                 // It is not valid to use an app token with other system types; we will
                 // instead make a new token for it (as if null had been passed in for the token).
                 attrs.token = null;
-                token = new WindowToken(this, null, type, false, displayContent,
+                token = new WindowToken(this, client.asBinder(), type, false, displayContent,
                         session.mCanAddInternalSystemWindow);
             }
 
diff --git a/services/tests/servicestests/src/com/android/server/wm/WindowTestUtils.java b/services/tests/servicestests/src/com/android/server/wm/WindowTestUtils.java
index 47ced99..d9349ed 100644
--- a/services/tests/servicestests/src/com/android/server/wm/WindowTestUtils.java
+++ b/services/tests/servicestests/src/com/android/server/wm/WindowTestUtils.java
@@ -66,8 +66,7 @@
     /** Creates a {@link Task} and adds it to the specified {@link TaskStack}. */
     public static Task createTaskInStack(WindowManagerService service, TaskStack stack,
             int userId) {
-        final Task newTask = new Task(WindowTestUtils.sNextTaskId++, stack, userId, service, null,
-                EMPTY, 0, false,
+        final Task newTask = new Task(sNextTaskId++, stack, userId, service, null, EMPTY, 0, false,
                 false, new ActivityManager.TaskDescription(), null);
         stack.addTask(newTask, POSITION_TOP);
         return newTask;
@@ -92,7 +91,7 @@
     public static class TestAppWindowToken extends AppWindowToken {
 
         TestAppWindowToken(DisplayContent dc) {
-            super(dc.mService, null, false, dc, true /* fillsParent */,
+            super(dc.mService, new IApplicationToken.Stub() {}, false, dc, true /* fillsParent */,
                     null /* overrideConfig */, null /* bounds */);
         }