diff --git a/daemon/src/main/java/org/lsposed/lspd/service/ActivityManagerService.java b/daemon/src/main/java/org/lsposed/lspd/service/ActivityManagerService.java
index 1d158894..b96fba17 100644
--- a/daemon/src/main/java/org/lsposed/lspd/service/ActivityManagerService.java
+++ b/daemon/src/main/java/org/lsposed/lspd/service/ActivityManagerService.java
@@ -26,6 +26,7 @@ import android.app.IActivityManager;
 import android.app.IApplicationThread;
 import android.app.IServiceConnection;
 import android.app.ProfilerInfo;
+import android.content.Context;
 import android.content.IContentProvider;
 import android.content.IIntentReceiver;
 import android.content.Intent;
@@ -58,8 +59,8 @@ public class ActivityManagerService {
     };
 
     public static IActivityManager getActivityManager() {
-        if (binder == null && am == null) {
-            binder = ServiceManager.getService("activity");
+        if (binder == null || am == null) {
+            binder = ServiceManager.getService(Context.ACTIVITY_SERVICE);
             if (binder == null) return null;
             try {
                 binder.linkToDeath(deathRecipient, 0);
diff --git a/daemon/src/main/java/org/lsposed/lspd/service/PackageService.java b/daemon/src/main/java/org/lsposed/lspd/service/PackageService.java
index 41357de1..e04601e2 100644
--- a/daemon/src/main/java/org/lsposed/lspd/service/PackageService.java
+++ b/daemon/src/main/java/org/lsposed/lspd/service/PackageService.java
@@ -92,7 +92,7 @@ public class PackageService {
     };
 
     private static IPackageManager getPackageManager() {
-        if (binder == null && pm == null) {
+        if (binder == null || pm == null) {
             binder = ServiceManager.getService("package");
             if (binder == null) return null;
             try {
diff --git a/daemon/src/main/java/org/lsposed/lspd/service/UserService.java b/daemon/src/main/java/org/lsposed/lspd/service/UserService.java
index 3fa8cd06..ee98969e 100644
--- a/daemon/src/main/java/org/lsposed/lspd/service/UserService.java
+++ b/daemon/src/main/java/org/lsposed/lspd/service/UserService.java
@@ -21,6 +21,7 @@ package org.lsposed.lspd.service;
 
 import static org.lsposed.lspd.service.ServiceManager.TAG;
 
+import android.content.Context;
 import android.content.pm.UserInfo;
 import android.os.Build;
 import android.os.IBinder;
@@ -53,8 +54,8 @@ public class UserService {
     }
 
     public static IUserManager getUserManager() {
-        if (binder == null && um == null) {
-            binder = ServiceManager.getService("user");
+        if (binder == null || um == null) {
+            binder = ServiceManager.getService(Context.USER_SERVICE);
             if (binder == null) return null;
             try {
                 binder.linkToDeath(recipient, 0);
diff --git a/hiddenapi/stubs/src/main/java/android/os/IUserManager.java b/hiddenapi/stubs/src/main/java/android/os/IUserManager.java
index 91aa7968..f2295d0b 100644
--- a/hiddenapi/stubs/src/main/java/android/os/IUserManager.java
+++ b/hiddenapi/stubs/src/main/java/android/os/IUserManager.java
@@ -17,7 +17,7 @@ public interface IUserManager extends IInterface {
     List<UserInfo> getUsers(boolean excludePartial, boolean excludeDying, boolean excludePreCreated)
             throws RemoteException;
 
-    UserInfo getUserInfo(int userHandle);
+    UserInfo getUserInfo(int userHandle) throws RemoteException;
 
     UserInfo getProfileParent(int userId) throws RemoteException;