diff --git a/services/core/java/com/android/server/PackageWatchdog.java b/services/core/java/com/android/server/PackageWatchdog.java
index d9e7c38519063..e77458cc955a1 100644
--- a/services/core/java/com/android/server/PackageWatchdog.java
+++ b/services/core/java/com/android/server/PackageWatchdog.java
@@ -315,28 +315,31 @@ public class PackageWatchdog {
         // causing any elapsed time to be deducted from all existing packages before we add new
         // packages. This maintains the invariant that the elapsed time for ALL (new and existing)
         // packages is the same.
-        syncState("observing new packages");
+        mLongTaskHandler.post(() -> {
+            syncState("observing new packages");
 
-        synchronized (mLock) {
-            ObserverInternal oldObserver = mAllObservers.get(observer.getName());
-            if (oldObserver == null) {
-                Slog.d(TAG, observer.getName() + " started monitoring health "
-                        + "of packages " + packageNames);
-                mAllObservers.put(observer.getName(),
-                        new ObserverInternal(observer.getName(), packages));
-            } else {
-                Slog.d(TAG, observer.getName() + " added the following "
-                        + "packages to monitor " + packageNames);
-                oldObserver.updatePackagesLocked(packages);
+            synchronized (mLock) {
+                ObserverInternal oldObserver = mAllObservers.get(observer.getName());
+                if (oldObserver == null) {
+                    Slog.d(TAG, observer.getName() + " started monitoring health "
+                            + "of packages " + packageNames);
+                    mAllObservers.put(observer.getName(),
+                            new ObserverInternal(observer.getName(), packages));
+                } else {
+                    Slog.d(TAG, observer.getName() + " added the following "
+                            + "packages to monitor " + packageNames);
+                    oldObserver.updatePackagesLocked(packages);
+                }
             }
-        }
 
-        // Register observer in case not already registered
-        registerHealthObserver(observer);
+            // Register observer in case not already registered
+            registerHealthObserver(observer);
+
+            // Sync after we add the new packages to the observers. We may have received packges
+            // requiring an earlier schedule than we are currently scheduled for.
+            syncState("updated observers");
+        });
 
-        // Sync after we add the new packages to the observers. We may have received packges
-        // requiring an earlier schedule than we are currently scheduled for.
-        syncState("updated observers");
     }
 
     /**