diff --git a/hmp.c b/hmp.c
index 9509596..c405d3e 100644
--- a/hmp.c
+++ b/hmp.c
@@ -284,27 +284,32 @@ void hmp_info_migrate_parameters(Monitor *mon, const QDict *qdict)

     if (params) {
         monitor_printf(mon, "parameters:");
+        assert(params->has_compress_level);
         monitor_printf(mon, " %s: %" PRId64,
             MigrationParameter_lookup[MIGRATION_PARAMETER_COMPRESS_LEVEL],
             params->compress_level);
+        assert(params->has_compress_threads);
         monitor_printf(mon, " %s: %" PRId64,
             MigrationParameter_lookup[MIGRATION_PARAMETER_COMPRESS_THREADS],
             params->compress_threads);
+        assert(params->has_decompress_threads);
         monitor_printf(mon, " %s: %" PRId64,
             MigrationParameter_lookup[MIGRATION_PARAMETER_DECOMPRESS_THREADS],
             params->decompress_threads);
+        assert(params->has_cpu_throttle_initial);
         monitor_printf(mon, " %s: %" PRId64,
             MigrationParameter_lookup[MIGRATION_PARAMETER_CPU_THROTTLE_INITIAL],
             params->cpu_throttle_initial);
+        assert(params->has_cpu_throttle_increment);
         monitor_printf(mon, " %s: %" PRId64,
             MigrationParameter_lookup[MIGRATION_PARAMETER_CPU_THROTTLE_INCREMENT],
             params->cpu_throttle_increment);
         monitor_printf(mon, " %s: '%s'",
             MigrationParameter_lookup[MIGRATION_PARAMETER_TLS_CREDS],
-            params->tls_creds ? : "");
+            params->has_tls_creds ? params->tls_creds : "");
         monitor_printf(mon, " %s: '%s'",
             MigrationParameter_lookup[MIGRATION_PARAMETER_TLS_HOSTNAME],
-            params->tls_hostname ? : "");
+            params->has_tls_hostname ? params->tls_hostname : "");
         monitor_printf(mon, "\n");
     }

diff --git a/migration/migration.c b/migration/migration.c
index 955d5ee..1a8f26b 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -559,12 +559,19 @@ MigrationParameters *qmp_query_migrate_parameters(Error **errp)
     MigrationState *s = migrate_get_current();

     params = g_malloc0(sizeof(*params));
+    params->has_compress_level = true;
     params->compress_level = s->parameters.compress_level;
+    params->has_compress_threads = true;
     params->compress_threads = s->parameters.compress_threads;
+    params->has_decompress_threads = true;
     params->decompress_threads = s->parameters.decompress_threads;
+    params->has_cpu_throttle_initial = true;
     params->cpu_throttle_initial = s->parameters.cpu_throttle_initial;
+    params->has_cpu_throttle_increment = true;
     params->cpu_throttle_increment = s->parameters.cpu_throttle_increment;
+    params->has_tls_creds = !!s->parameters.tls_creds;
     params->tls_creds = g_strdup(s->parameters.tls_creds);
+    params->has_tls_hostname = !!s->parameters.tls_hostname;
     params->tls_hostname = g_strdup(s->parameters.tls_hostname);

     return params;
diff --git a/qapi-schema.json b/qapi-schema.json
index 9e47b47..e16e889 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -668,40 +668,53 @@
 #
 # @migrate-set-parameters
 #
-# Set the following migration parameters
-#
-# @compress-level: compression level
-#
-# @compress-threads: compression thread count
-#
-# @decompress-threads: decompression thread count
-#
-# @cpu-throttle-initial: Initial percentage of time guest cpus are throttled
-#                        when migration auto-converge is activated. The
-#                        default value is 20. (Since 2.7)
-#
-# @cpu-throttle-increment: throttle percentage increase each time
-#                          auto-converge detects that migration is not making
-#                          progress. The default value is 10. (Since 2.7)
-#
-# @tls-creds: ID of the 'tls-creds' object that provides credentials for
-#             establishing a TLS connection over the migration data channel.
-#             On the outgoing side of the migration, the credentials must
-#             be for a 'client' endpoint, while for the incoming side the
-#             credentials must be for a 'server' endpoint. Setting this
-#             will enable TLS for all migrations. The default is unset,
-#             resulting in unsecured migration at the QEMU level. (Since 2.7)
-#
-# @tls-hostname: hostname of the target host for the migration. This is
-#                required when using x509 based TLS credentials and the
-#                migration URI does not already include a hostname. For
-#                example if using fd: or exec: based migration, the
-#                hostname must be provided so that the server's x509
-#                certificate identity can be validated. (Since 2.7)
+# Set various migration parameters.  See MigrationParameters for details.
 #
 # Since: 2.4
 ##
 { 'command': 'migrate-set-parameters',
+  'data': 'MigrationParameters' }
+
+#
+# @MigrationParameters
+#
+# Optional members can be omitted on input ('migrate-set-parameters')
+# but most members will always be present on output
+# ('query-migrate-parameters'), with the exception of tls-creds and
+# tls-hostname.
+#
+# @compress-level: #optional compression level
+#
+# @compress-threads: #optional compression thread count
+#
+# @decompress-threads: #optional decompression thread count
+#
+# @cpu-throttle-initial: #optional Initial percentage of time guest cpus are
+#                        throttledwhen migration auto-converge is activated.
+#                        The default value is 20. (Since 2.7)
+#
+# @cpu-throttle-increment: #optional throttle percentage increase each time
+#                          auto-converge detects that migration is not making
+#                          progress. The default value is 10. (Since 2.7)
+#
+# @tls-creds: #optional ID of the 'tls-creds' object that provides credentials
+#             for establishing a TLS connection over the migration data
+#             channel. On the outgoing side of the migration, the credentials
+#             must be for a 'client' endpoint, while for the incoming side the
+#             credentials must be for a 'server' endpoint. Setting this
+#             will enable TLS for all migrations. The default is unset,
+#             resulting in unsecured migration at the QEMU level. (Since 2.7)
+#
+# @tls-hostname: #optional hostname of the target host for the migration. This
+#                is required when using x509 based TLS credentials and the
+#                migration URI does not already include a hostname. For
+#                example if using fd: or exec: based migration, the
+#                hostname must be provided so that the server's x509
+#                certificate identity can be validated. (Since 2.7)
+#
+# Since: 2.4
+##
+{ 'struct': 'MigrationParameters',
   'data': { '*compress-level': 'int',
             '*compress-threads': 'int',
             '*decompress-threads': 'int',
@@ -709,50 +722,6 @@
             '*cpu-throttle-increment': 'int',
             '*tls-creds': 'str',
             '*tls-hostname': 'str'} }
-
-#
-# @MigrationParameters
-#
-# @compress-level: compression level
-#
-# @compress-threads: compression thread count
-#
-# @decompress-threads: decompression thread count
-#
-# @cpu-throttle-initial: Initial percentage of time guest cpus are throttled
-#                        when migration auto-converge is activated. The
-#                        default value is 20. (Since 2.7)
-#
-# @cpu-throttle-increment: throttle percentage increase each time
-#                          auto-converge detects that migration is not making
-#                          progress. The default value is 10. (Since 2.7)
-#
-# @tls-creds: ID of the 'tls-creds' object that provides credentials for
-#             establishing a TLS connection over the migration data channel.
-#             On the outgoing side of the migration, the credentials must
-#             be for a 'client' endpoint, while for the incoming side the
-#             credentials must be for a 'server' endpoint. Setting this
-#             will enable TLS for all migrations. The default is unset,
-#             resulting in unsecured migration at the QEMU level. (Since 2.7)
-#
-# @tls-hostname: hostname of the target host for the migration. This is
-#                required when using x509 based TLS credentials and the
-#                migration URI does not already include a hostname. For
-#                example if using fd: or exec: based migration, the
-#                hostname must be provided so that the server's x509
-#                certificate identity can be validated. (Since 2.7)
-#
-# Since: 2.4
-##
-{ 'struct': 'MigrationParameters',
-  'data': { 'compress-level': 'int',
-            'compress-threads': 'int',
-            'decompress-threads': 'int',
-            'cpu-throttle-initial': 'int',
-            'cpu-throttle-increment': 'int',
-            'tls-creds': 'str',
-            'tls-hostname': 'str'} }
-
 ##
 # @query-migrate-parameters
 #
