diff --git a/bin/elastipubsub/main.c b/bin/elastipubsub/main.c
index 04085169..1745fe9a 100644
--- a/bin/elastipubsub/main.c
+++ b/bin/elastipubsub/main.c
@@ -37,7 +37,7 @@ struct app_ctx {
     struct aws_mutex lock;
     struct aws_condition_variable signal;
     struct aws_uri uri;
-    uint16_t port;
+    uint32_t port;
     const char *cacert;
     const char *cert;
     const char *key;
diff --git a/bin/elastipubsub5/main.c b/bin/elastipubsub5/main.c
index f3ac686b..2c84e796 100644
--- a/bin/elastipubsub5/main.c
+++ b/bin/elastipubsub5/main.c
@@ -44,7 +44,7 @@ struct app_ctx {
     struct aws_mutex lock;
     struct aws_condition_variable signal;
     struct aws_uri uri;
-    uint16_t port;
+    uint32_t port;
     const char *cacert;
     const char *cert;
     const char *key;
diff --git a/bin/mqtt5canary/main.c b/bin/mqtt5canary/main.c
index cf7c50bc..4431d8f0 100644
--- a/bin/mqtt5canary/main.c
+++ b/bin/mqtt5canary/main.c
@@ -45,7 +45,7 @@ struct app_ctx {
     struct aws_mutex lock;
     struct aws_condition_variable signal;
     struct aws_uri uri;
-    uint16_t port;
+    uint32_t port;
     const char *cacert;
     const char *cert;
     const char *key;
@@ -181,7 +181,7 @@ static void s_parse_options(
                 ctx->use_websockets = true;
                 break;
             case 'p':
-                ctx->port = (uint16_t)atoi(aws_cli_optarg);
+                ctx->port = (uint32_t)atoi(aws_cli_optarg);
                 break;
             case 't':
                 tester_options->elg_max_threads = (uint16_t)atoi(aws_cli_optarg);
diff --git a/include/aws/mqtt/client.h b/include/aws/mqtt/client.h
index de2934a7..8d85bfe8 100644
--- a/include/aws/mqtt/client.h
+++ b/include/aws/mqtt/client.h
@@ -254,7 +254,7 @@ struct aws_mqtt_topic_subscription {
  */
 struct aws_mqtt_connection_options {
     struct aws_byte_cursor host_name;
-    uint16_t port;
+    uint32_t port;
     struct aws_socket_options *socket_options;
     struct aws_tls_connection_options *tls_options;
     struct aws_byte_cursor client_id;
diff --git a/include/aws/mqtt/private/client_impl.h b/include/aws/mqtt/private/client_impl.h
index 4dc13cf4..1d0dd67a 100644
--- a/include/aws/mqtt/private/client_impl.h
+++ b/include/aws/mqtt/private/client_impl.h
@@ -199,7 +199,7 @@ struct aws_mqtt_client_connection_311_impl {
 
     /* The host information, changed by user when state is AWS_MQTT_CLIENT_STATE_DISCONNECTED */
     struct aws_string *host_name;
-    uint16_t port;
+    uint32_t port;
     struct aws_tls_connection_options tls_options;
     struct aws_socket_options socket_options;
     struct aws_http_proxy_config *http_proxy_config;
diff --git a/include/aws/mqtt/private/v5/mqtt5_options_storage.h b/include/aws/mqtt/private/v5/mqtt5_options_storage.h
index 9fe14817..22e39e83 100644
--- a/include/aws/mqtt/private/v5/mqtt5_options_storage.h
+++ b/include/aws/mqtt/private/v5/mqtt5_options_storage.h
@@ -141,7 +141,7 @@ struct aws_mqtt5_client_options_storage {
     struct aws_allocator *allocator;
 
     struct aws_string *host_name;
-    uint16_t port;
+    uint32_t port;
     struct aws_client_bootstrap *bootstrap;
     struct aws_socket_options socket_options;
 
diff --git a/include/aws/mqtt/v5/mqtt5_client.h b/include/aws/mqtt/v5/mqtt5_client.h
index 2f92e124..d04d2981 100644
--- a/include/aws/mqtt/v5/mqtt5_client.h
+++ b/include/aws/mqtt/v5/mqtt5_client.h
@@ -526,7 +526,7 @@ struct aws_mqtt5_client_options {
     /**
      * Port to establish mqtt connections to
      */
-    uint16_t port;
+    uint32_t port;
 
     /**
      * Client bootstrap to use whenever this client establishes a connection
diff --git a/source/v5/mqtt5_options_storage.c b/source/v5/mqtt5_options_storage.c
index 68a06a88..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);
         }
     }
@@ -3542,7 +3548,7 @@ void aws_mqtt5_client_options_storage_log(
         log_handle,
         level,
         AWS_LS_MQTT5_GENERAL,
-        "id=%p: aws_mqtt5_client_options_storage port set to %" PRIu16,
+        "id=%p: aws_mqtt5_client_options_storage port set to %" PRIu32,
         (void *)options_storage,
         options_storage->port);
 
@@ -3603,7 +3609,7 @@ void aws_mqtt5_client_options_storage_log(
             log_handle,
             level,
             AWS_LS_MQTT5_GENERAL,
-            "id=%p: aws_mqtt5_client_options_storage http proxy port set to %" PRIu16,
+            "id=%p: aws_mqtt5_client_options_storage http proxy port set to %" PRIu32,
             (void *)options_storage,
             options_storage->http_proxy_options.port);
 
diff --git a/source/v5/mqtt5_to_mqtt3_adapter.c b/source/v5/mqtt5_to_mqtt3_adapter.c
index e48ca3d3..129c0132 100644
--- a/source/v5/mqtt5_to_mqtt3_adapter.c
+++ b/source/v5/mqtt5_to_mqtt3_adapter.c
@@ -199,7 +199,7 @@ struct aws_mqtt_adapter_connect_task {
     struct aws_mqtt_client_connection_5_impl *adapter;
 
     struct aws_byte_buf host_name;
-    uint16_t port;
+    uint32_t port;
     struct aws_socket_options socket_options;
     struct aws_tls_connection_options *tls_options_ptr;
     struct aws_tls_connection_options tls_options;
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..80c0f978 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 +1184,12 @@ 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) {                                                                  \