diff --git a/wolfssl/internal.h b/wolfssl/internal.h
index 37cf731ae2..cf991f3105 100644
--- a/wolfssl/internal.h
+++ b/wolfssl/internal.h
@@ -1636,7 +1636,11 @@ enum Misc {
     SERVER_ID_LEN = WC_SHA_DIGEST_SIZE,
 #endif
 
+#ifdef WOLFSSL_DTLS13
+    HANDSHAKE_HEADER_SZ   = 12, /* big enough to hold Dtls13HandshakeHeader */
+#else
     HANDSHAKE_HEADER_SZ   = 4,  /* type + length(3)        */
+#endif
     RECORD_HEADER_SZ      = 5,  /* type + version + len(2) */
     CERT_HEADER_SZ        = 3,  /* always 3 bytes          */
     REQ_HEADER_SZ         = 2,  /* cert request header sz  */