diff --git a/trunk/src/app/srs_app_http.cpp b/trunk/src/app/srs_app_http.cpp
index a5831086b..56ecd1aea 100644
--- a/trunk/src/app/srs_app_http.cpp
+++ b/trunk/src/app/srs_app_http.cpp
@@ -1441,7 +1441,7 @@ int SrsHttpParser::parse_message_imp(SrsStSocket* skt)
         }
         
         // consume the parsed bytes.
-        if (nparsed && header_parsed && nparsed - header_parsed >= 0) {
+        if (nparsed && header_parsed && (nparsed - header_parsed >= 0)) {
             buffer->read_slice(header_parsed);
             header_parsed = 0;
         }