diff --git a/mpp/mpp.cpp b/mpp/mpp.cpp
index cd1d264a..cd94e0c2 100644
--- a/mpp/mpp.cpp
+++ b/mpp/mpp.cpp
@@ -110,6 +110,10 @@ Mpp::~Mpp ()
 
 void Mpp::clear()
 {
+    // MUST: release listener here
+    if (mFrameGroup)
+        mpp_buffer_group_set_listener((MppBufferGroupImpl *)mFrameGroup, NULL);
+
     if (mThreadCodec)
         mThreadCodec->stop();
     if (mThreadHal)
diff --git a/mpp/mpp_buffer_impl.cpp b/mpp/mpp_buffer_impl.cpp
index 2f28a0dc..1a91a296 100644
--- a/mpp/mpp_buffer_impl.cpp
+++ b/mpp/mpp_buffer_impl.cpp
@@ -433,6 +433,7 @@ MPP_RET mpp_buffer_group_set_listener(MppBufferGroupImpl *p, void *listener)
         return MPP_ERR_NULL_PTR;
     }
 
+    Mutex::Autolock auto_lock(&service.mLock);
     p->listener = listener;
 
     return MPP_OK;