diff --git a/trunk/src/libs/srs_librtmp.cpp b/trunk/src/libs/srs_librtmp.cpp
index 21851bcdb..1233bd172 100644
--- a/trunk/src/libs/srs_librtmp.cpp
+++ b/trunk/src/libs/srs_librtmp.cpp
@@ -28,6 +28,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 // for srs-librtmp, @see https://github.com/simple-rtmp-server/srs/issues/213
 #ifndef _WIN32
 #include <sys/time.h>
+#include <unistd.h>
 #endif
 
 #include <string>
diff --git a/trunk/src/libs/srs_librtmp.hpp b/trunk/src/libs/srs_librtmp.hpp
index a39f44510..ffa074f0f 100644
--- a/trunk/src/libs/srs_librtmp.hpp
+++ b/trunk/src/libs/srs_librtmp.hpp
@@ -927,8 +927,8 @@ extern const char* srs_human_format_time();
     #define srs_human_verbose(msg, ...) (void)0
     #define srs_human_raw(msg, ...) (void)0
 #else
-    #define srs_human_trace(msg, ...) printf("[%s] ", srs_human_format_time());printf(msg, ##__VA_ARGS__);printf("\n")
-    #define srs_human_verbose(msg, ...) printf("[%s] ", srs_human_format_time());printf(msg, ##__VA_ARGS__);printf("\n")
+    #define srs_human_trace(msg, ...) printf("[%s][%d] ", srs_human_format_time(), getpid());printf(msg, ##__VA_ARGS__);printf("\n")
+    #define srs_human_verbose(msg, ...) printf("[%s][%d] ", srs_human_format_time(), getpid());printf(msg, ##__VA_ARGS__);printf("\n")
     #define srs_human_raw(msg, ...) printf(msg, ##__VA_ARGS__)
 #endif
 
@@ -943,6 +943,8 @@ typedef void* srs_hijack_io_t;
     #ifndef _WIN32
         // for iovec.
         #include <sys/uio.h>
+        // for getpid.
+        #include <unistd.h>
     #endif
     /**
     * get the hijack io object in rtmp protocol sdk.