diff --git a/mbtk/mbtk_gnssd/gnss_main.c b/mbtk/mbtk_gnssd/gnss_main.c
index 3f887f1..9510f3d 100755
--- a/mbtk/mbtk_gnssd/gnss_main.c
+++ b/mbtk/mbtk_gnssd/gnss_main.c
@@ -8,11 +8,12 @@
 #include <libubus.h>
 #include <signal.h>
 #include <cutils/properties.h>
+#include <ctype.h>
 
 #include "mbtk_type.h"
 #include "mbtk_log.h"
 #include "gnss_info.h"
-
+#include "gnss_utils.h"
 #include "gnss_6228.h"
 #include "gnss_hd8122.h"
 #include "gnss_asr5311.h"
@@ -511,10 +512,10 @@
     return count;
 }
 #else
-int gnss_write(int fd, const void* buf, unsigned int buf_len)
+int gnss_write(int fd, const void* buf, int buf_len)
 {
-    size_t size;
-    size_t size_to_wr;
+    ssize_t size;
+    ssize_t size_to_wr;
     ssize_t size_written;
     if(GNSS_BUFF_SIZE < buf_len)
     {
@@ -526,7 +527,7 @@
         if( size_to_wr > GNSS_BUFF_SIZE)
             size_to_wr = GNSS_BUFF_SIZE;
 
-        size_written = write(fd, &buf[size], size_to_wr);
+        size_written = write(fd, (const uint8*)buf + size, size_to_wr);
         if (size_written==-1)
         {
             return -1;