diff --git a/services/core/java/com/android/server/am/ActivityStack.java b/services/core/java/com/android/server/am/ActivityStack.java
index 8b7a6af8a7008..7d7520a8e3850 100644
--- a/services/core/java/com/android/server/am/ActivityStack.java
+++ b/services/core/java/com/android/server/am/ActivityStack.java
@@ -2508,9 +2508,11 @@ final class ActivityStack {
         }
 
         int taskNdx = mTaskHistory.indexOf(task);
-        do {
-            taskTop = mTaskHistory.get(taskNdx--).getTopActivity();
-        } while (taskTop == null && taskNdx >= 0);
+        if (taskNdx >= 0) {
+            do {
+                taskTop = mTaskHistory.get(taskNdx--).getTopActivity();
+            } while (taskTop == null && taskNdx >= 0);
+        }
 
         if (topOptions != null) {
             // If we got some ActivityOptions from an activity on top that