diff --git a/src/fast_buffer.c b/src/fast_buffer.c
index ddf3439..9ffa6c8 100644
--- a/src/fast_buffer.c
+++ b/src/fast_buffer.c
@@ -80,7 +80,7 @@ int fast_buffer_append(FastBuffer *buffer, const char *format, ...)
     int result;
     int len;
 
-    if ((result=fast_buffer_check(buffer, 10)) != 0)
+    if ((result=fast_buffer_check(buffer, 64)) != 0)
     {
         return result;
     }
@@ -102,8 +102,12 @@ int fast_buffer_append(FastBuffer *buffer, const char *format, ...)
                     buffer->alloc_size - buffer->length, format, ap);
             va_end(ap);
         }
+        else
+        {
+            *(buffer->data + buffer->length) = '\0';  //restore
+        }
     }
-    return 0;
+    return result;
 }
 
 int fast_buffer_append_buff(FastBuffer *buffer, const char *data, const int len)
diff --git a/src/fast_buffer.h b/src/fast_buffer.h
index 6b46d74..e1a1e92 100644
--- a/src/fast_buffer.h
+++ b/src/fast_buffer.h
@@ -30,6 +30,14 @@ static inline int fast_buffer_init(FastBuffer *buffer)
     return fast_buffer_init_ex(buffer, 0);
 }
 
+#define fast_buffer_clear(buffer) fast_buffer_reset(buffer)
+
+static inline void fast_buffer_reset(FastBuffer *buffer)
+{
+    buffer->length = 0;
+    *buffer->data = '\0';
+}
+
 void fast_buffer_destroy(FastBuffer *buffer);
 
 int fast_buffer_append(FastBuffer *buffer, const char *format, ...);
@@ -45,6 +53,11 @@ static inline int fast_buffer_append_string(FastBuffer *buffer, const char *str)
     return fast_buffer_append_buff(buffer, str, strlen(str));
 }
 
+static inline int fast_buffer_append_buffer(FastBuffer *buffer, FastBuffer *src)
+{
+    return fast_buffer_append_buff(buffer, src->data, src->length);
+}
+
 #ifdef __cplusplus
 }
 #endif