diff --git a/src/tools/qtprotobufgen/qprotobufgenerator.cpp b/src/tools/qtprotobufgen/qprotobufgenerator.cpp
index b136fe33..68b216f2 100644
--- a/src/tools/qtprotobufgen/qprotobufgenerator.cpp
+++ b/src/tools/qtprotobufgen/qprotobufgenerator.cpp
@@ -40,7 +40,6 @@ bool QProtobufGenerator::Generate(const FileDescriptor *file,
 {
     assert(file != nullptr);
     assert(generatorContext != nullptr);
-
     return GenerateMessages(file, generatorContext);
 }
 
@@ -266,6 +265,7 @@ void QProtobufGenerator::GenerateHeader(const FileDescriptor *file,
     }
 
     bool hasOneofFields = false;
+    bool hasOptionalFields = false;
     std::unordered_set<std::string> qtTypesSet;
     common::iterateMessages(
             file, [&](const Descriptor *message) {
@@ -286,12 +286,23 @@ void QProtobufGenerator::GenerateHeader(const FileDescriptor *file,
                                                 + "/" + field->message_type()->name());
                         qtTypesSet.insert(field->message_type()->file()->package());
                     }
+                    if (field->has_optional_keyword())
+                        hasOptionalFields = true;
                 }
             });
 
     if (hasOneofFields)
         externalIncludes.insert("QtProtobuf/qprotobufoneof.h");
 
+    if (hasOptionalFields) {
+        std::cerr << "WARNING: '" << file->name() << "' contains 'optional' fields.\n"
+                     "\nOptional fields are not supported in this qtprotobufgen version\n"
+                     "The generator disregards the keyword, but generates the regular\n"
+                     "fields instead.\n"
+                     "\nPlease upgrade Qt to the most recent version to get full support\n"
+                     "of the 'optional' fields.\n";
+    }
+
     for (const auto &qtTypeInclude: qtTypesSet) {
         std::string qtTypeLower = qtTypeInclude;
         std::transform(qtTypeLower.begin(), qtTypeLower.end(),
diff --git a/src/tools/qtprotoccommon/generatorbase.cpp b/src/tools/qtprotoccommon/generatorbase.cpp
index 5a49a0a1..00b453bb 100644
--- a/src/tools/qtprotoccommon/generatorbase.cpp
+++ b/src/tools/qtprotoccommon/generatorbase.cpp
@@ -29,6 +29,11 @@ bool GeneratorBase::GenerateAll(const std::vector<const FileDescriptor *> &files
     return CodeGenerator::GenerateAll(files, parameter, generatorContext, error);
 }
 
+uint64_t GeneratorBase::GetSupportedFeatures() const
+{
+    return CodeGenerator::Feature::FEATURE_PROTO3_OPTIONAL;
+}
+
 std::string GeneratorBase::generateBaseName(const FileDescriptor *file, const std::string &name)
 {
     std::string outFileBasename;
diff --git a/src/tools/qtprotoccommon/generatorbase.h b/src/tools/qtprotoccommon/generatorbase.h
index 7a95504b..e1b52cf0 100644
--- a/src/tools/qtprotoccommon/generatorbase.h
+++ b/src/tools/qtprotoccommon/generatorbase.h
@@ -37,6 +37,8 @@ public:
                      std::string *error) const override;
     bool HasGenerateAll() const override { return true; }
 
+    uint64_t GetSupportedFeatures() const override;
+
     static void printDisclaimer(::google::protobuf::io::Printer *printer);
     void OpenFileNamespaces(const ::google::protobuf::FileDescriptor *file,
                             google::protobuf::io::Printer *printer) const;
diff --git a/tests/auto/protobuf/CMakeLists.txt b/tests/auto/protobuf/CMakeLists.txt
index 3fbf2651..114da540 100644
--- a/tests/auto/protobuf/CMakeLists.txt
+++ b/tests/auto/protobuf/CMakeLists.txt
@@ -14,6 +14,7 @@ if(TARGET Qt6::qtprotobufgen)
     add_subdirectory(converters)
     add_subdirectory(duplicated_metatypes)
     add_subdirectory(recursive)
+    add_subdirectory(optional)
     if(TARGET Qt6::ProtobufWellKnownTypes)
         add_subdirectory(wellknown)
     endif()
diff --git a/tests/auto/protobuf/optional/CMakeLists.txt b/tests/auto/protobuf/optional/CMakeLists.txt
new file mode 100644
index 00000000..84007d9e
--- /dev/null
+++ b/tests/auto/protobuf/optional/CMakeLists.txt
@@ -0,0 +1,24 @@
+# Copyright (C) 2022 The Qt Company Ltd.
+# SPDX-License-Identifier: BSD-3-Clause
+
+if(NOT QT_BUILD_STANDALONE_TESTS AND NOT QT_BUILDING_QT)
+    cmake_minimum_required(VERSION 3.16)
+    project(tst_protobuf_optional LANGUAGES CXX)
+    find_package(Qt6BuildInternals REQUIRED COMPONENTS STANDALONE_TEST)
+endif()
+
+qt_internal_add_test(tst_protobuf_optional
+    SOURCES
+        tst_protobuf_optional.cpp
+    INCLUDE_DIRECTORIES
+        ../shared
+    LIBRARIES
+        Qt::Test
+        Qt::Protobuf
+)
+qt_autogen_tools_initial_setup(tst_protobuf_optional)
+
+qt6_add_protobuf(tst_protobuf_optional
+    PROTO_FILES
+        ../../shared/data/proto/optional.proto
+)
diff --git a/tests/auto/protobuf/optional/tst_protobuf_optional.cpp b/tests/auto/protobuf/optional/tst_protobuf_optional.cpp
new file mode 100644
index 00000000..8fd604c5
--- /dev/null
+++ b/tests/auto/protobuf/optional/tst_protobuf_optional.cpp
@@ -0,0 +1,14 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+
+#include <QTest>
+#include <QObject>
+
+class QtProtobufOptionalTest : public QObject
+{
+    Q_OBJECT
+};
+
+QTEST_MAIN(QtProtobufOptionalTest)
+
+#include "tst_protobuf_optional.moc"
diff --git a/tests/auto/shared/data/proto/optional.proto b/tests/auto/shared/data/proto/optional.proto
new file mode 100644
index 00000000..2636b9c6
--- /dev/null
+++ b/tests/auto/shared/data/proto/optional.proto
@@ -0,0 +1,9 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
+syntax = "proto3";
+
+package qtprotobufnamespace.optional.tests;
+
+message OptionalMessage {
+    optional sint32 testField = 2;
+}