diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 83f2b3c..2fcc950 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -4241,7 +4241,7 @@
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "There is pending outgoing data" ) );
         return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
     }
-    /* Protocol must be DLTS, not TLS */
+    /* Protocol must be DTLS, not TLS */
     if( ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "Only DTLS is supported" ) );