diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index eb332b8..62db474 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -4660,7 +4660,7 @@
         rec.data_len    = ssl->in_msglen;
         rec.data_offset = 0;
 #if defined(MBEDTLS_SSL_CID )
-        rec.cid_len     = ssl->in_len - ssl->in_cid;
+        rec.cid_len     = (uint8_t)( ssl->in_len - ssl->in_cid );
         memcpy( rec.cid, ssl->in_cid, rec.cid_len );
 #endif /* MBEDTLS_SSL_CID */