diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 5f6ae62..60357e2 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -6526,7 +6526,9 @@
         cur_len = strlen( *p );
         tot_len += cur_len;
 
-        if( cur_len == 0 || cur_len > 255 || tot_len > 65535 )
+        if( ( cur_len == 0 ) ||
+            ( cur_len > MBEDTLS_SSL_MAX_ALPN_NAME_LEN ) ||
+            ( tot_len > MBEDTLS_SSL_MAX_ALPN_LIST_LEN ) )
             return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
     }