diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index c9051a4..451370c 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -101,6 +101,8 @@
     if( servername_list_size + 2 != len )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
     }
 
@@ -111,6 +113,8 @@
         if( hostname_len + 3 > servername_list_size )
         {
             MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
+            mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                            MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
             return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
         }
 
@@ -135,6 +139,8 @@
     if( servername_list_size != 0 )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
     }
 
@@ -201,6 +207,8 @@
         sig_alg_list_size % 2 != 0 )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
     }
 
@@ -247,6 +255,8 @@
         list_size % 2 != 0 )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
     }
 
@@ -254,6 +264,8 @@
     if( ssl->handshake->curves != NULL )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
     }
 
@@ -264,7 +276,11 @@
         our_size = MBEDTLS_ECP_DP_MAX;
 
     if( ( curves = mbedtls_calloc( our_size, sizeof( *curves ) ) ) == NULL )
+    {
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR );
         return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
+    }
 
     ssl->handshake->curves = curves;
 
@@ -297,6 +313,8 @@
     if( list_size + 1 != len )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
     }
 
@@ -342,6 +360,8 @@
                                                 buf, len ) ) != 0 )
     {
         MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecjpake_read_round_one", ret );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
         return( ret );
     }
 
@@ -360,6 +380,8 @@
     if( len != 1 || buf[0] >= MBEDTLS_SSL_MAX_FRAG_LEN_INVALID )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
     }
 
@@ -377,6 +399,8 @@
     if( len != 0 )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
     }
 
@@ -397,6 +421,8 @@
     if( len != 0 )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
     }
 
@@ -420,6 +446,8 @@
     if( len != 0 )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
     }
 
@@ -531,11 +559,19 @@
 
     /* Min length is 2 (list_len) + 1 (name_len) + 1 (name) */
     if( len < 4 )
+    {
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
+    }
 
     list_len = ( buf[0] << 8 ) | buf[1];
     if( list_len != len - 2 )
+    {
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
+    }
 
     /*
      * Use our order of preference
@@ -549,13 +585,21 @@
         {
             /* If the list is well formed, we should get equality first */
             if( theirs > end )
+            {
+                mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                                MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
                 return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
+            }
 
             cur_len = *theirs++;
 
             /* Empty strings MUST NOT be included */
             if( cur_len == 0 )
+            {
+                mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                                MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
                 return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
+            }
 
             if( cur_len == ours_len &&
                 memcmp( theirs, *ours, cur_len ) == 0 )
@@ -1064,6 +1108,9 @@
 }
 #endif /* MBEDTLS_SSL_SRV_SUPPORT_SSLV2_CLIENT_HELLO */
 
+/* This function doesn't alert on errors that happen early during
+   ClientHello parsing because they might indicate that the client is
+   not talking SSL/TLS at all and would not understand our alert. */
 static int ssl_parse_client_hello( mbedtls_ssl_context *ssl )
 {
     int ret, got_common_suite;
@@ -1098,6 +1145,7 @@
     {
         if( ( ret = mbedtls_ssl_fetch_input( ssl, 5 ) ) != 0 )
         {
+            /* No alert on a read error. */
             MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_fetch_input", ret );
             return( ret );
         }
@@ -1349,10 +1397,8 @@
                             " [%d:%d] < [%d:%d]",
                             ssl->major_ver, ssl->minor_ver,
                             ssl->conf->min_major_ver, ssl->conf->min_minor_ver ) );
-
         mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
                                      MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION );
-
         return( MBEDTLS_ERR_SSL_BAD_HS_PROTOCOL_VERSION );
     }
 
@@ -1380,6 +1426,8 @@
         sess_len + 34 + 2 > msg_len ) /* 2 for cipherlist length field */
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
     }
 
@@ -1403,6 +1451,8 @@
         if( cookie_offset + 1 + cookie_len + 2 > msg_len )
         {
             MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
+            mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                            MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION );
             return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
         }
 
@@ -1435,6 +1485,7 @@
             /* We know we didn't send a cookie, so it should be empty */
             if( cookie_len != 0 )
             {
+                /* This may be an attacker's probe, so don't send an alert */
                 MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
                 return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
             }
@@ -1459,6 +1510,8 @@
         ( ciph_len % 2 ) != 0 )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
     }
 
@@ -1477,6 +1530,8 @@
         comp_len + comp_offset + 1 > msg_len )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
     }
 
@@ -1515,6 +1570,8 @@
             if( msg_len < ext_offset + 2 )
             {
                 MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
+                mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                                MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
                 return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
             }
 
@@ -1525,6 +1582,8 @@
                 msg_len != ext_offset + 2 + ext_len )
             {
                 MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
+                mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                                MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
                 return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
             }
         }
@@ -1544,6 +1603,8 @@
             if( ext_size + 4 > ext_len )
             {
                 MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
+                mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                                MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
                 return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
             }
             switch( ext_id )
@@ -1689,6 +1750,8 @@
             if( ext_len > 0 && ext_len < 4 )
             {
                 MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
+                mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                                MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
                 return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
             }
         }