diff --git a/source/v5/mqtt5_options_storage.c b/source/v5/mqtt5_options_storage.c
index 5e41bb20..975e52e3 100644
--- a/source/v5/mqtt5_options_storage.c
+++ b/source/v5/mqtt5_options_storage.c
@@ -3356,14 +3356,20 @@ int aws_mqtt5_client_options_validate(const struct aws_mqtt5_client_options *opt
         }
     }
 
+    if (aws_socket_validate_port_for_connect(
+            options->port, options->socket_options ? options->socket_options->domain : AWS_SOCKET_IPV4)) {
+        AWS_LOGF_ERROR(AWS_LS_MQTT5_GENERAL, "invalid port in mqtt5 client configuration");
+        return aws_raise_error(AWS_ERROR_MQTT5_CLIENT_OPTIONS_VALIDATION);
+    }
+
     if (options->http_proxy_options != NULL) {
         if (options->http_proxy_options->host.len == 0) {
             AWS_LOGF_ERROR(AWS_LS_MQTT5_GENERAL, "proxy host name not set in mqtt5 client configuration");
             return aws_raise_error(AWS_ERROR_MQTT5_CLIENT_OPTIONS_VALIDATION);
         }
 
-        if (options->http_proxy_options->port == 0) {
-            AWS_LOGF_ERROR(AWS_LS_MQTT5_GENERAL, "proxy port not set in mqtt5 client configuration");
+        if (aws_socket_validate_port_for_connect(options->http_proxy_options->port, AWS_SOCKET_IPV4)) {
+            AWS_LOGF_ERROR(AWS_LS_MQTT5_GENERAL, "invalid proxy port in mqtt5 client configuration");
             return aws_raise_error(AWS_ERROR_MQTT5_CLIENT_OPTIONS_VALIDATION);
         }
     }
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 3494aa2e..b8ef2587 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -244,6 +244,7 @@ add_test_case(mqtt5_client_options_validation_failure_no_publish_received)
 add_test_case(mqtt5_client_options_validation_failure_invalid_socket_options)
 add_test_case(mqtt5_client_options_validation_failure_invalid_connect)
 add_test_case(mqtt5_client_options_validation_failure_invalid_keep_alive)
+add_test_case(mqtt5_client_options_validation_failure_invalid_port)
 add_test_case(mqtt5_operation_subscribe_connection_settings_validation_failure_exceeds_maximum_packet_size)
 add_test_case(mqtt5_operation_unsubscribe_connection_settings_validation_failure_exceeds_maximum_packet_size)
 add_test_case(mqtt5_operation_publish_connection_settings_validation_failure_exceeds_maximum_packet_size)
diff --git a/tests/v5/mqtt5_operation_validation_failure_tests.c b/tests/v5/mqtt5_operation_validation_failure_tests.c
index 1bb2b814..6573eeaf 100644
--- a/tests/v5/mqtt5_operation_validation_failure_tests.c
+++ b/tests/v5/mqtt5_operation_validation_failure_tests.c
@@ -1113,6 +1113,7 @@ static struct aws_mqtt5_client_options s_good_client_options = {
             .ptr = s_server_reference,
             .len = AWS_ARRAY_SIZE(s_server_reference) - 1,
         },
+    .port = 1883,
     .socket_options = &s_good_socket_options,
     .connect_options = &s_good_connect,
     .ping_timeout_ms = 5000,
@@ -1183,6 +1184,15 @@ AWS_CLIENT_CREATION_VALIDATION_FAILURE(
     s_good_client_options,
     s_make_invalid_keep_alive_client_options)
 
+static void s_make_invalid_port_client_options(struct aws_mqtt5_client_options *options) {
+    options->port = 0xFFFFFFFF;
+}
+
+AWS_CLIENT_CREATION_VALIDATION_FAILURE(
+    invalid_port,
+    s_good_client_options,
+    s_make_invalid_port_client_options)
+
 #define AWS_CONNECTION_SETTINGS_VALIDATION_FAILURE_TEST_PREFIX(packet_type, failure_reason, init_success_settings_fn)  \
     static int s_mqtt5_operation_##packet_type##_connection_settings_validation_failure_##failure_reason##_fn(         \
         struct aws_allocator *allocator, void *ctx) {                                                                  \