diff --git a/lib/spdylay_helper.c b/lib/spdylay_helper.c
index d1bc8bc2..9243886d 100644
--- a/lib/spdylay_helper.c
+++ b/lib/spdylay_helper.c
@@ -57,6 +57,7 @@ int spdylay_reserve_buffer(uint8_t **buf_ptr, size_t *buflen_ptr,
                            size_t min_length)
 {
   if(min_length > *buflen_ptr) {
+    min_length = (min_length+4095)/4096*4096;
     uint8_t *temp = malloc(min_length);
     if(temp == NULL) {
       return SPDYLAY_ERR_NOMEM;