diff --git a/whale/src/android/art/art_hook_param.h b/whale/src/android/art/art_hook_param.h
index dc11eb8..ecaef27 100644
--- a/whale/src/android/art/art_hook_param.h
+++ b/whale/src/android/art/art_hook_param.h
@@ -18,7 +18,7 @@ struct ArtHookParam final {
     u4 origin_code_item_off;
     jobject origin_method_;
     jobject hooked_method_;
-    ptr_t decl_class_;
+    volatile ptr_t decl_class_;
     jobject class_Loader_;
     jmethodID hooked_native_method_;
     jmethodID origin_native_method_;
diff --git a/whale/src/android/art/art_jni_trampoline.cc b/whale/src/android/art/art_jni_trampoline.cc
index a2384c6..f0f1a82 100644
--- a/whale/src/android/art/art_jni_trampoline.cc
+++ b/whale/src/android/art/art_jni_trampoline.cc
@@ -12,6 +12,10 @@ namespace whale {
 namespace art {
 
 static void UnBoxValue(JNIEnv *env, jvalue *jv, jobject obj, char type) {
+    if (obj == nullptr) {
+        jv->l = obj;
+        return;
+    }
     switch (type) {
         case 'I':
             jv->i = Types::FromInteger(env, obj);
diff --git a/whale/src/android/art/art_runtime.cc b/whale/src/android/art/art_runtime.cc
index 66ccdaa..f763fa4 100644
--- a/whale/src/android/art/art_runtime.cc
+++ b/whale/src/android/art/art_runtime.cc
@@ -175,6 +175,7 @@ bool ArtRuntime::OnLoad(JavaVM *vm, JNIEnv *env, jclass java_class) {
     CHECK_FIELD(quick_generic_jni_trampoline, nullptr)
     class_linker_objects_.quick_generic_jni_trampoline_ = quick_generic_jni_trampoline;
 
+    pthread_mutex_init(&mutex, nullptr);
     EnforceDisableHiddenAPIPolicy();
     return true;
 
@@ -267,19 +268,23 @@ ArtRuntime::InvokeOriginalMethod(jlong slot, jobject this_object, jobjectArray a
     ArtMethod hooked_method(param->hooked_native_method_);
     ptr_t decl_class = hooked_method.GetDeclaringClass();
     if (param->decl_class_ != decl_class) {
-        ScopedSuspendAll suspend_all;
-        LOG(INFO)
-                << "Notice: MovingGC cause the GcRoot References changed.";
-        jobject origin_java_method = hooked_method.Clone(env, param->origin_access_flags);
-        jmethodID origin_jni_method = env->FromReflectedMethod(origin_java_method);
-        ArtMethod origin_method(origin_jni_method);
-        origin_method.SetEntryPointFromQuickCompiledCode(param->origin_compiled_code_);
-        origin_method.SetEntryPointFromJni(param->origin_jni_code_);
-        origin_method.SetDexCodeItemOffset(param->origin_code_item_off);
-        param->origin_native_method_ = origin_jni_method;
-        env->DeleteGlobalRef(param->origin_method_);
-        param->origin_method_ = env->NewGlobalRef(origin_java_method);
-        param->decl_class_ = decl_class;
+        pthread_mutex_lock(&mutex);
+        if (param->decl_class_ != decl_class) {
+            ScopedSuspendAll suspend_all;
+            LOG(INFO)
+                    << "Notice: MovingGC cause the GcRoot References changed.";
+            jobject origin_java_method = hooked_method.Clone(env, param->origin_access_flags);
+            jmethodID origin_jni_method = env->FromReflectedMethod(origin_java_method);
+            ArtMethod origin_method(origin_jni_method);
+            origin_method.SetEntryPointFromQuickCompiledCode(param->origin_compiled_code_);
+            origin_method.SetEntryPointFromJni(param->origin_jni_code_);
+            origin_method.SetDexCodeItemOffset(param->origin_code_item_off);
+            param->origin_native_method_ = origin_jni_method;
+            env->DeleteGlobalRef(param->origin_method_);
+            param->origin_method_ = env->NewGlobalRef(origin_java_method);
+            param->decl_class_ = decl_class;
+        }
+        pthread_mutex_unlock(&mutex);
     }
 
     jobject ret = env->CallNonvirtualObjectMethod(
diff --git a/whale/src/android/art/art_runtime.h b/whale/src/android/art/art_runtime.h
index a0da8e5..fe88cde 100644
--- a/whale/src/android/art/art_runtime.h
+++ b/whale/src/android/art/art_runtime.h
@@ -137,6 +137,7 @@ class ArtRuntime final {
     ClassLinkerObjects class_linker_objects_;
     ArtMethodOffsets method_offset_;
     std::map<jmethodID, ArtHookParam *> hooked_method_map_;
+    pthread_mutex_t mutex;
 
     bool EnforceDisableHiddenAPIPolicyImpl();