diff --git a/trunk/src/kernel/srs_kernel_mp4.cpp b/trunk/src/kernel/srs_kernel_mp4.cpp
index 5cfc5ac9f..2fcedd52d 100644
--- a/trunk/src/kernel/srs_kernel_mp4.cpp
+++ b/trunk/src/kernel/srs_kernel_mp4.cpp
@@ -2744,10 +2744,10 @@ SrsMp4DataEntryBox* SrsMp4DataReferenceBox::entry_at(int index)
     return entries.at(index);
 }
 
-SrsMp4DataReferenceBox* SrsMp4DataReferenceBox::append(SrsMp4DataEntryBox* v)
+// Note that box must be SrsMp4DataEntryBox*
+void SrsMp4DataReferenceBox::append(SrsMp4Box* box)
 {
-    entries.push_back(v);
-    return this;
+    entries.push_back((SrsMp4DataEntryBox*)box);
 }
 
 int SrsMp4DataReferenceBox::nb_header()
@@ -3765,10 +3765,10 @@ SrsMp4SampleEntry* SrsMp4SampleDescriptionBox::entrie_at(int index)
     return entries.at(index);
 }
 
-SrsMp4SampleDescriptionBox* SrsMp4SampleDescriptionBox::append(SrsMp4SampleEntry* v)
+// Note that box must be SrsMp4SampleEntry*
+void SrsMp4SampleDescriptionBox::append(SrsMp4Box* box)
 {
-    entries.push_back(v);
-    return this;
+    entries.push_back((SrsMp4SampleEntry*)box);
 }
 
 int SrsMp4SampleDescriptionBox::nb_header()
diff --git a/trunk/src/kernel/srs_kernel_mp4.hpp b/trunk/src/kernel/srs_kernel_mp4.hpp
index 161f2c032..4b4919530 100644
--- a/trunk/src/kernel/srs_kernel_mp4.hpp
+++ b/trunk/src/kernel/srs_kernel_mp4.hpp
@@ -1173,7 +1173,8 @@ public:
 public:
     virtual uint32_t entry_count();
     virtual SrsMp4DataEntryBox* entry_at(int index);
-    virtual SrsMp4DataReferenceBox* append(SrsMp4DataEntryBox* v);
+    // Note that box must be SrsMp4DataEntryBox*
+    virtual void append(SrsMp4Box* box);
 protected:
     virtual int nb_header();
     virtual srs_error_t encode_header(SrsBuffer* buf);
@@ -1520,7 +1521,8 @@ public:
 public:
     virtual uint32_t entry_count();
     virtual SrsMp4SampleEntry* entrie_at(int index);
-    virtual SrsMp4SampleDescriptionBox* append(SrsMp4SampleEntry* v);
+    // Note that box must be SrsMp4SampleEntry*
+    virtual void append(SrsMp4Box* box);
 protected:
     virtual int nb_header();
     virtual srs_error_t encode_header(SrsBuffer* buf);