diff --git a/components/libc/compilers/newlib/syscalls.c b/components/libc/compilers/newlib/syscalls.c
index 59c1881ad1..228fa0d140 100644
--- a/components/libc/compilers/newlib/syscalls.c
+++ b/components/libc/compilers/newlib/syscalls.c
@@ -17,10 +17,6 @@
 #include <dfs_posix.h>
 #endif
 
-#ifdef RT_USING_PTHREADS
-#include <pthread.h>
-#endif
-
 #ifdef RT_USING_MODULE
 #include <dlmodule.h>
 #endif
diff --git a/components/libc/pthreads/SConscript b/components/libc/pthreads/SConscript
index 1b7b75bfd1..e154ee0aa9 100644
--- a/components/libc/pthreads/SConscript
+++ b/components/libc/pthreads/SConscript
@@ -1,10 +1,22 @@
 from building import *
+from utils import VersionCmp
 
-cwd = GetCurrentDir()
-src	= Glob('*.c')
-CPPPATH = [cwd]
+cwd        = GetCurrentDir()
+src        = Glob('*.c')
+CPPPATH    = [cwd]
+CPPDEFINES = []
+
+# only enable POSIX.1b-1993 Real-time extensions
+libc_ver   = GetDepend('LIBC_VERSION')
+try:
+    ver = libc_ver.split(' ')
+    ver = ver[1]
+    if VersionCmp(ver, "2.5.0") == 1:
+        CPPDEFINES = ['_POSIX_C_SOURCE=199309L']
+except :
+    pass
 
 group = DefineGroup('pthreads', src, 
-    depend = ['RT_USING_PTHREADS', 'RT_USING_LIBC'], CPPPATH = CPPPATH)
+    depend = ['RT_USING_PTHREADS', 'RT_USING_LIBC'], CPPPATH = CPPPATH, CPPDEFINES = CPPDEFINES)
 
 Return('group')
diff --git a/components/libc/pthreads/pthread.c b/components/libc/pthreads/pthread.c
old mode 100755
new mode 100644
index 5d3bc0796a..19a511b45b
--- a/components/libc/pthreads/pthread.c
+++ b/components/libc/pthreads/pthread.c
@@ -277,7 +277,7 @@ int pthread_create(pthread_t            *pid,
 
     /* set pthread cleanup function and ptd data */
     ptd->tid->cleanup = _pthread_cleanup;
-    ptd->tid->user_data = (rt_uint32_t)ptd;
+    ptd->tid->user_data = (rt_ubase_t)ptd;
 
     /* start thread */
     if (rt_thread_startup(ptd->tid) == RT_EOK)
diff --git a/include/rtdef.h b/include/rtdef.h
index f2b546f75e..b391ff7685 100644
--- a/include/rtdef.h
+++ b/include/rtdef.h
@@ -623,7 +623,7 @@ struct rt_thread
     void        *lwp;
 #endif
 
-    rt_uint32_t user_data;                             /**< private user data beyond this thread */
+    rt_ubase_t user_data;                             /**< private user data beyond this thread */
 };
 typedef struct rt_thread *rt_thread_t;