diff --git a/programs/ssl/ssl_server2.c b/programs/ssl/ssl_server2.c
index 27ffbb9..27f2312 100644
--- a/programs/ssl/ssl_server2.c
+++ b/programs/ssl/ssl_server2.c
@@ -259,7 +259,8 @@
 
 #if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
 #define USAGE_PSK_RAW                                               \
-    "    psk=%%s              default: \"\" (in hex, without 0x)\n"     \
+    "    psk=%%s              default: \"\" (disabled)\n"     \
+    "                          The PSK values are in hex, without 0x.\n" \
     "    psk_list=%%s         default: \"\"\n"                          \
     "                          A list of (PSK identity, PSK value) pairs.\n" \
     "                          The PSK values are in hex, without 0x.\n" \
@@ -3364,12 +3365,16 @@
         }
         else
 #endif /* MBEDTLS_USE_PSA_CRYPTO */
-        if( ( ret = mbedtls_ssl_conf_psk( &conf, psk, psk_len,
-                                     (const unsigned char *) opt.psk_identity,
-                                     strlen( opt.psk_identity ) ) ) != 0 )
+        if( psk_len > 0 )
         {
-            mbedtls_printf( "  failed\n  mbedtls_ssl_conf_psk returned -0x%04X\n\n", - ret );
-            goto exit;
+            ret = mbedtls_ssl_conf_psk( &conf, psk, psk_len,
+                                     (const unsigned char *) opt.psk_identity,
+                                     strlen( opt.psk_identity ) );
+            if( ret != 0 )
+            {
+                mbedtls_printf( "  failed\n  mbedtls_ssl_conf_psk returned -0x%04X\n\n", - ret );
+                goto exit;
+            }
         }
     }