diff --git a/trunk/src/app/srs_app_server.cpp b/trunk/src/app/srs_app_server.cpp
index dc5873696..d69c6c066 100644
--- a/trunk/src/app/srs_app_server.cpp
+++ b/trunk/src/app/srs_app_server.cpp
@@ -230,9 +230,16 @@ int SrsListener::cycle()
 #ifdef SRS_AUTO_STREAM_CASTER
 SrsUdpListener::SrsUdpListener(SrsServer* server, SrsListenerType type, SrsConfDirective* c) : SrsListener(server, type)
 {
+    _type = type;
     nb_buf = SRS_UDP_MAX_PACKET_SIZE;
     buf = new char[nb_buf];
-    caster = new SrsMpegtsOverUdp(c);
+
+    // the caller already ensure the type is ok,
+    // we just assert here for unknown stream caster.
+    srs_assert(_type == SrsListenerMpegTsOverUdp);
+    if (_type == SrsListenerMpegTsOverUdp) {
+        caster = new SrsMpegtsOverUdp(c);
+    }
 }
 
 SrsUdpListener::~SrsUdpListener()
diff --git a/trunk/src/core/srs_core.hpp b/trunk/src/core/srs_core.hpp
index 8e441ace4..2377ef845 100644
--- a/trunk/src/core/srs_core.hpp
+++ b/trunk/src/core/srs_core.hpp
@@ -31,7 +31,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 // current release version
 #define VERSION_MAJOR       2
 #define VERSION_MINOR       0
-#define VERSION_REVISION    103
+#define VERSION_REVISION    104
 
 // server info.
 #define RTMP_SIG_SRS_KEY "SRS"