diff --git a/src/buffer.c b/src/buffer.c
index e8c96a3..4a27e57 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -3,6 +3,7 @@
 #include <stdio.h>
 #include <stdarg.h>
 #include "ucore/buffer.h"
+#include "ucore/utils.h"
  
 GBuf*
 uc_new_gbuf(size_t initsz)
@@ -48,7 +49,7 @@ uc_gbuf_append(GBuf *buf,const void *data,size_t len)
     unsigned char *gbuf;
     
     if (buf->len - buf->used < len)
-        if (uc_gbuf_grow(buf, len + len/2))
+        if (uc_gbuf_grow(buf, len + UC_MAX(UC_MIN(8U,len/2),256U)))
             return -1;
 
     gbuf = buf->buf;