diff --git a/trunk/src/kernel/srs_kernel_utility.cpp b/trunk/src/kernel/srs_kernel_utility.cpp
index aebee90c59..4e75b06f24 100644
--- a/trunk/src/kernel/srs_kernel_utility.cpp
+++ b/trunk/src/kernel/srs_kernel_utility.cpp
@@ -269,6 +269,32 @@ string srs_string_remove(string str, string remove_chars)
     return ret;
 }
 
+string srs_erase_first_substr(string str, string erase_string)
+{
+	std::string ret = str;
+
+	size_t pos = ret.find(erase_string);
+
+	if (pos != std::string::npos)
+	{
+		ret.erase(pos, erase_string.length());
+	}
+	return ret;
+}
+
+string srs_erase_last_substr(string str, string erase_string)
+{
+	std::string ret = str;
+
+	size_t pos = ret.rfind(erase_string);
+
+	if (pos != std::string::npos)
+	{
+		ret.erase(pos, erase_string.length());
+	}
+	return ret;
+}
+
 bool srs_string_ends_with(string str, string flag)
 {
     return str.rfind(flag) == str.length() - flag.length();
diff --git a/trunk/src/kernel/srs_kernel_utility.hpp b/trunk/src/kernel/srs_kernel_utility.hpp
index ad5dd5765b..0850748482 100644
--- a/trunk/src/kernel/srs_kernel_utility.hpp
+++ b/trunk/src/kernel/srs_kernel_utility.hpp
@@ -63,6 +63,10 @@ extern std::string srs_string_trim_end(std::string str, std::string trim_chars);
 extern std::string srs_string_trim_start(std::string str, std::string trim_chars);
 // remove char in remove_chars of str
 extern std::string srs_string_remove(std::string str, std::string remove_chars);
+// remove first substring from str
+extern std::string srs_erase_first_substr(std::string str, std::string erase_string);
+// remove last substring from str
+extern std::string srs_erase_last_substr(std::string str, std::string erase_string);
 // whether string end with
 extern bool srs_string_ends_with(std::string str, std::string flag);
 // whether string starts with
diff --git a/trunk/src/protocol/srs_rtmp_utility.cpp b/trunk/src/protocol/srs_rtmp_utility.cpp
index c322a97968..b050488f02 100644
--- a/trunk/src/protocol/srs_rtmp_utility.cpp
+++ b/trunk/src/protocol/srs_rtmp_utility.cpp
@@ -90,6 +90,9 @@ void srs_vhost_resolve(string& vhost, string& app, string& param)
     app = srs_string_replace(app, "...", "?");
     app = srs_string_replace(app, "&&", "?");
     app = srs_string_replace(app, "=", "?");
+    if (srs_string_ends_with(app, "/_definst_")){
+        app = srs_erase_last_substr(app, "/_definst_");
+    }
     
     if ((pos = app.find("?")) != std::string::npos) {
         std::string query = app.substr(pos + 1);
diff --git a/trunk/src/utest/srs_utest_kernel.cpp b/trunk/src/utest/srs_utest_kernel.cpp
index 46e82bcda3..5fd07a9bd1 100644
--- a/trunk/src/utest/srs_utest_kernel.cpp
+++ b/trunk/src/utest/srs_utest_kernel.cpp
@@ -1514,6 +1514,18 @@ VOID TEST(KernelUtilityTest, UtilityString)
     
     str1 = srs_string_remove(str, "ol");
     EXPECT_STREQ("He, Wrd! He, SRS!", str1.c_str());
+
+    str1 = srs_erase_first_substr(str, "Hello");
+    EXPECT_STREQ(", World! Hello, SRS!", str1.c_str());
+
+    str1 = srs_erase_first_substr(str, "XX");
+    EXPECT_STREQ("Hello, World! Hello, SRS!", str1.c_str());
+
+    str1 = srs_erase_last_substr(str, "Hello");
+    EXPECT_STREQ("Hello, World! , SRS!", str1.c_str());
+
+    str1 = srs_erase_last_substr(str, "XX");
+    EXPECT_STREQ("Hello, World! Hello, SRS!", str1.c_str());
     
     EXPECT_FALSE(srs_string_ends_with("Hello", "x"));
     EXPECT_TRUE(srs_string_ends_with("Hello", "o"));
diff --git a/trunk/src/utest/srs_utest_protocol.cpp b/trunk/src/utest/srs_utest_protocol.cpp
index 9bd2cc3f71..119acfd3ba 100644
--- a/trunk/src/utest/srs_utest_protocol.cpp
+++ b/trunk/src/utest/srs_utest_protocol.cpp
@@ -579,6 +579,16 @@ VOID TEST(ProtocolUtilityTest, DiscoveryTcUrl)
     EXPECT_STREQ("live", app.c_str());
     EXPECT_STREQ("show", stream.c_str());
     EXPECT_STREQ("19351", port.c_str());
+
+    // _definst_ at the end of app
+    tcUrl = "rtmp://winlin.cn/live/_definst_"; stream= "show";
+    srs_discovery_tc_url(tcUrl, schema, ip, vhost, app, stream, port, param);
+    EXPECT_STREQ("rtmp", schema.c_str());
+    EXPECT_STREQ("winlin.cn", ip.c_str());
+    EXPECT_STREQ("winlin.cn", vhost.c_str());
+    EXPECT_STREQ("live", app.c_str());
+    EXPECT_STREQ("show", stream.c_str());
+    EXPECT_STREQ("1935", port.c_str());
 }
 
 /**