diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index f2e7ae7..82f8d83 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -287,7 +287,7 @@
 {
     int ret;
     unsigned char *p = buf;
-    const unsigned char *end = ssl->out_buf + MBEDTLS_SSL_MAX_CONTENT_LEN;
+    const unsigned char *end = ssl->out_msg + MBEDTLS_SSL_MAX_CONTENT_LEN;
     size_t kkpp_len;
 
     *olen = 0;