diff --git a/services/core/java/com/android/server/testharness/TestHarnessModeService.java b/services/core/java/com/android/server/testharness/TestHarnessModeService.java
index 52236a81c6070..8b2b8b1cfbace 100644
--- a/services/core/java/com/android/server/testharness/TestHarnessModeService.java
+++ b/services/core/java/com/android/server/testharness/TestHarnessModeService.java
@@ -284,6 +284,9 @@ public class TestHarnessModeService extends SystemService {
     private class TestHarnessModeShellCommand extends ShellCommand {
         @Override
         public int onCommand(String cmd) {
+            if (cmd == null) {
+                return handleDefaultCommands(cmd);
+            }
             switch (cmd) {
                 case "enable":
                 case "restore":