diff --git a/trunk/src/app/srs_app_latest_version.cpp b/trunk/src/app/srs_app_latest_version.cpp
index f588e17ff..801af6072 100644
--- a/trunk/src/app/srs_app_latest_version.cpp
+++ b/trunk/src/app/srs_app_latest_version.cpp
@@ -184,7 +184,7 @@ srs_error_t SrsLatestVersion::start()
 
         for (int i = 0; i < 16; i++) {
             int r0 = snprintf(buf + i * 2, sizeof(buf) - i * 2, "%02x", uuid[i]);
-            srs_assert(r0 > 0 && r0 < sizeof(buf) - i * 2);
+            srs_assert(r0 > 0 && r0 < (int)sizeof(buf) - i * 2);
         }
         server_id_ = buf;
     }
diff --git a/trunk/src/app/srs_app_listener.cpp b/trunk/src/app/srs_app_listener.cpp
index 12d4d1e5f..07f5d2e3f 100755
--- a/trunk/src/app/srs_app_listener.cpp
+++ b/trunk/src/app/srs_app_listener.cpp
@@ -436,7 +436,7 @@ std::string SrsUdpMuxSocket::peer_id()
         // Build the peer id, reserve 1 byte for the trailing '\0'.
         static char id_buf[128 + 1];
         int len = snprintf(id_buf, sizeof(id_buf), "%s:%d", peer_ip.c_str(), peer_port);
-        if (len <= 0 || len >= sizeof(id_buf)) {
+        if (len <= 0 || len >= (int)sizeof(id_buf)) {
             return "";
         }
         peer_id_ = string(id_buf, len);
diff --git a/trunk/src/protocol/srs_protocol_srt.cpp b/trunk/src/protocol/srs_protocol_srt.cpp
index fac1e3ae8..5bb02dfd3 100644
--- a/trunk/src/protocol/srs_protocol_srt.cpp
+++ b/trunk/src/protocol/srs_protocol_srt.cpp
@@ -171,7 +171,7 @@ srs_error_t srs_srt_listen(srs_srt_t srt_fd, std::string ip, int port)
 
     char sport[8];
     int r0 = snprintf(sport, sizeof(sport), "%d", port);
-    srs_assert(r0 > 0 && r0 < sizeof(sport));
+    srs_assert(r0 > 0 && r0 < (int)sizeof(sport));
 
     addrinfo hints;
     memset(&hints, 0, sizeof(hints));
diff --git a/trunk/src/protocol/srs_protocol_st.cpp b/trunk/src/protocol/srs_protocol_st.cpp
index ae98d4e74..73d2ed10a 100644
--- a/trunk/src/protocol/srs_protocol_st.cpp
+++ b/trunk/src/protocol/srs_protocol_st.cpp
@@ -176,7 +176,7 @@ srs_error_t srs_tcp_connect(string server, int port, srs_utime_t tm, srs_netfd_t
 
     char sport[8];
     int r0 = snprintf(sport, sizeof(sport), "%d", port);
-    srs_assert(r0 > 0 && r0 < sizeof(sport));
+    srs_assert(r0 > 0 && r0 < (int)sizeof(sport));
     
     addrinfo hints;
     memset(&hints, 0, sizeof(hints));
@@ -253,7 +253,7 @@ srs_error_t srs_tcp_listen(std::string ip, int port, srs_netfd_t* pfd)
 
     char sport[8];
     int r0 = snprintf(sport, sizeof(sport), "%d", port);
-    srs_assert(r0 > 0 && r0 < sizeof(sport));
+    srs_assert(r0 > 0 && r0 < (int)sizeof(sport));
 
     addrinfo hints;
     memset(&hints, 0, sizeof(hints));
@@ -315,7 +315,7 @@ srs_error_t srs_udp_listen(std::string ip, int port, srs_netfd_t* pfd)
 
     char sport[8];
     int r0 = snprintf(sport, sizeof(sport), "%d", port);
-    srs_assert(r0 > 0 && r0 < sizeof(sport));
+    srs_assert(r0 > 0 && r0 < (int)sizeof(sport));
 
     addrinfo hints;
     memset(&hints, 0, sizeof(hints));