diff --git a/src/configuration/configuration.cpp b/src/configuration/configuration.cpp
index 7e3599dfb..72ef5ed2e 100644
--- a/src/configuration/configuration.cpp
+++ b/src/configuration/configuration.cpp
@@ -273,6 +273,8 @@ ConstString KEY_AUDIO_OUTPUT_DEVICE = "Audio output device";
 ConstString KEY_MAXIMUM_NUMBER_OF_PATHS = "maximum number of paths";
 ConstString KEY_MULTIPLE_CONNECTIONS_PENALTY = "multiple connections penalty";
 ConstString KEY_MUME_START_EPOCH = "Mume start epoch";
+ConstString KEY_GMCP_BROADCAST_CLOCK = "GMCP broadcast clock";
+ConstString KEY_GMCP_BROADCAST_INTERVAL = "GMCP broadcast interval";
 ConstString KEY_NUMBER_OF_ANTI_ALIASING_SAMPLES = "Number of anti-aliasing samples";
 ConstString KEY_PROXY_CONNECTION_STATUS = "Proxy connection status";
 ConstString KEY_PROXY_LISTENS_ON_ANY_INTERFACE = "Proxy listens on any interface";
@@ -752,6 +754,8 @@ void Configuration::MumeClockSettings::read(const QSettings &conf)
     // NOTE: old values might be stored as int32
     startEpoch = conf.value(KEY_MUME_START_EPOCH, 1517443173).toLongLong();
     display = conf.value(KEY_DISPLAY_CLOCK, true).toBool();
+    gmcpBroadcast = conf.value(KEY_GMCP_BROADCAST_CLOCK, true).toBool();
+    gmcpBroadcastInterval = conf.value(KEY_GMCP_BROADCAST_INTERVAL, 2500).toInt();
 }
 
 void Configuration::AdventurePanelSettings::read(const QSettings &conf)
@@ -933,6 +937,8 @@ void Configuration::MumeClockSettings::write(QSettings &conf) const
     // Note: There's no QVariant(int64_t) constructor.
     conf.setValue(KEY_MUME_START_EPOCH, static_cast<qlonglong>(startEpoch));
     conf.setValue(KEY_DISPLAY_CLOCK, display);
+    conf.setValue(KEY_GMCP_BROADCAST_CLOCK, gmcpBroadcast);
+    conf.setValue(KEY_GMCP_BROADCAST_INTERVAL, gmcpBroadcastInterval);
 }
 
 void Configuration::AdventurePanelSettings::write(QSettings &conf) const
diff --git a/src/configuration/configuration.h b/src/configuration/configuration.h
index bd535c640..6ade92f19 100644
--- a/src/configuration/configuration.h
+++ b/src/configuration/configuration.h
@@ -311,6 +311,8 @@ class NODISCARD Configuration final
     {
         int64_t startEpoch = 0;
         bool display = false;
+        bool gmcpBroadcast = true;
+        int gmcpBroadcastInterval = 2500;
 
     private:
         SUBGROUP();
diff --git a/src/opengl/OpenGLProber.cpp b/src/opengl/OpenGLProber.cpp
index c0160bf3b..64e76c499 100644
--- a/src/opengl/OpenGLProber.cpp
+++ b/src/opengl/OpenGLProber.cpp
@@ -13,6 +13,7 @@
 #include <QOpenGLContext>
 
 #ifdef WIN32
+#include <windows.h>
 extern "C" {
 // Prefer discrete nVidia and AMD GPUs by default on Windows
 __declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001;
diff --git a/src/preferences/mumeprotocolpage.cpp b/src/preferences/mumeprotocolpage.cpp
index b1016b09c..4d45d710d 100644
--- a/src/preferences/mumeprotocolpage.cpp
+++ b/src/preferences/mumeprotocolpage.cpp
@@ -30,6 +30,14 @@ MumeProtocolPage::MumeProtocolPage(QWidget *parent)
             &QAbstractButton::clicked,
             this,
             &MumeProtocolPage::slot_externalEditorBrowseButtonClicked);
+    connect(ui->gmcpBroadcastCheckBox,
+            &QCheckBox::stateChanged,
+            this,
+            &MumeProtocolPage::slot_gmcpBroadcastCheckBoxChanged);
+    connect(ui->gmcpIntervalSpinBox,
+            QOverload<int>::of(&QSpinBox::valueChanged),
+            this,
+            &MumeProtocolPage::slot_gmcpIntervalSpinBoxChanged);
 }
 
 MumeProtocolPage::~MumeProtocolPage()
@@ -49,6 +57,11 @@ void MumeProtocolPage::slot_loadConfig()
     if constexpr (CURRENT_PLATFORM == PlatformEnum::Wasm) {
         ui->externalEditorRadioButton->setDisabled(true);
     }
+
+    const auto &clockSettings = getConfig().mumeClock;
+    ui->gmcpBroadcastCheckBox->setChecked(clockSettings.gmcpBroadcast);
+    ui->gmcpIntervalSpinBox->setValue(clockSettings.gmcpBroadcastInterval);
+    ui->gmcpIntervalSpinBox->setEnabled(clockSettings.gmcpBroadcast);
 }
 
 void MumeProtocolPage::slot_internalEditorRadioButtonChanged(bool /*unused*/)
@@ -78,3 +91,15 @@ void MumeProtocolPage::slot_externalEditorBrowseButtonClicked(bool /*unused*/)
         command = quotedFileName;
     }
 }
+
+void MumeProtocolPage::slot_gmcpBroadcastCheckBoxChanged(int /*unused*/)
+{
+    const bool enabled = ui->gmcpBroadcastCheckBox->isChecked();
+    setConfig().mumeClock.gmcpBroadcast = enabled;
+    ui->gmcpIntervalSpinBox->setEnabled(enabled);
+}
+
+void MumeProtocolPage::slot_gmcpIntervalSpinBoxChanged(int value)
+{
+    setConfig().mumeClock.gmcpBroadcastInterval = value;
+}
diff --git a/src/preferences/mumeprotocolpage.h b/src/preferences/mumeprotocolpage.h
index 583d528d9..d39411f93 100644
--- a/src/preferences/mumeprotocolpage.h
+++ b/src/preferences/mumeprotocolpage.h
@@ -31,4 +31,6 @@ public slots:
     void slot_internalEditorRadioButtonChanged(bool);
     void slot_externalEditorCommandTextChanged(QString);
     void slot_externalEditorBrowseButtonClicked(bool);
+    void slot_gmcpBroadcastCheckBoxChanged(int);
+    void slot_gmcpIntervalSpinBoxChanged(int);
 };
diff --git a/src/preferences/mumeprotocolpage.ui b/src/preferences/mumeprotocolpage.ui
index e509334ef..1ed062d61 100644
--- a/src/preferences/mumeprotocolpage.ui
+++ b/src/preferences/mumeprotocolpage.ui
@@ -120,6 +120,51 @@
      </layout>
     </widget>
    </item>
+   <item>
+    <widget class="QGroupBox" name="gmcpClockGroupBox">
+     <property name="title">
+      <string>GMCP Clock Broadcasting</string>
+     </property>
+     <layout class="QGridLayout" name="gridLayout_2">
+      <item row="0" column="0" colspan="2">
+       <widget class="QCheckBox" name="gmcpBroadcastCheckBox">
+        <property name="text">
+         <string>Broadcast clock to connected clients (GMCP MUME.Time)</string>
+        </property>
+        <property name="checked">
+         <bool>true</bool>
+        </property>
+       </widget>
+      </item>
+      <item row="1" column="0">
+       <widget class="QLabel" name="gmcpIntervalLabel">
+        <property name="text">
+         <string>Update interval (ms):</string>
+        </property>
+       </widget>
+      </item>
+      <item row="1" column="1">
+       <widget class="QSpinBox" name="gmcpIntervalSpinBox">
+        <property name="toolTip">
+         <string>How often to send clock updates to clients (default: 2500ms = 1 MUME minute)</string>
+        </property>
+        <property name="minimum">
+         <number>500</number>
+        </property>
+        <property name="maximum">
+         <number>60000</number>
+        </property>
+        <property name="singleStep">
+         <number>500</number>
+        </property>
+        <property name="value">
+         <number>2500</number>
+        </property>
+       </widget>
+      </item>
+     </layout>
+    </widget>
+   </item>
    <item>
     <spacer>
      <property name="orientation">
diff --git a/src/proxy/GmcpMessage.h b/src/proxy/GmcpMessage.h
index 806e3b4a1..9e172e558 100644
--- a/src/proxy/GmcpMessage.h
+++ b/src/proxy/GmcpMessage.h
@@ -54,6 +54,7 @@ class ParseEvent;
     X(ROOM_CHARS_UPDATE, RoomCharsUpdate, "room.chars.update", "Room.Chars.Update") \
     X(ROOM_INFO, RoomInfo, "room.info", "Room.Info") \
     X(ROOM_UPDATE_EXITS, RoomUpdateExits, "room.update.exits", "Room.Update.Exits") \
+    X(MUME_TIME_INFO, MumeTimeInfo, "mume.time.info", "MUME.Time.Info") \
     /* define gmcp message types above */
 
 enum class NODISCARD GmcpMessageTypeEnum {
@@ -66,7 +67,7 @@ enum class NODISCARD GmcpMessageTypeEnum {
 #define X_COUNT(...) +1
 static constexpr const size_t NUM_GMCP_MESSAGES = XFOREACH_GMCP_MESSAGE_TYPE(X_COUNT);
 #undef X_COUNT
-static_assert(NUM_GMCP_MESSAGES == 30);
+static_assert(NUM_GMCP_MESSAGES == 31);
 DEFINE_ENUM_COUNT(GmcpMessageTypeEnum, NUM_GMCP_MESSAGES)
 
 namespace tags {
diff --git a/src/proxy/GmcpModule.h b/src/proxy/GmcpModule.h
index 90f03d26e..9e42f7c51 100644
--- a/src/proxy/GmcpModule.h
+++ b/src/proxy/GmcpModule.h
@@ -23,6 +23,7 @@
     X(MUME_CLIENT, MumeClient, "mume.client", "MUME.Client") \
     X(ROOM_CHARS, RoomChars, "room.chars", "Room.Chars") \
     X(ROOM, Room, "room", "Room") \
+    X(MUME_TIME, MumeTime, "mume.time", "MUME.Time") \
     /* define gmcp module types above */
 
 enum class NODISCARD GmcpModuleTypeEnum {
@@ -35,7 +36,7 @@ enum class NODISCARD GmcpModuleTypeEnum {
 #define X_COUNT(...) +1
 static constexpr const size_t NUM_GMCP_MODULES = XFOREACH_GMCP_MODULE_TYPE(X_COUNT);
 #undef X_COUNT
-static_assert(NUM_GMCP_MODULES == 7);
+static_assert(NUM_GMCP_MODULES == 8);
 DEFINE_ENUM_COUNT(GmcpModuleTypeEnum, NUM_GMCP_MODULES)
 
 namespace tags {
diff --git a/src/proxy/UserTelnet.cpp b/src/proxy/UserTelnet.cpp
index e02e2fdb3..45f78c5ff 100644
--- a/src/proxy/UserTelnet.cpp
+++ b/src/proxy/UserTelnet.cpp
@@ -261,12 +261,14 @@ void UserTelnet::receiveGmcpModule(const GmcpModule &mod, const bool enabled)
         m_gmcp.modules.insert(mod);
         if (mod.isSupported()) {
             m_gmcp.supported[mod.getType()] = mod.getVersion();
+            m_outputs.onGmcpModuleEnabled(mod.getType(), true);
         }
 
     } else {
         m_gmcp.modules.erase(mod);
         if (mod.isSupported()) {
             m_gmcp.supported[mod.getType()] = DEFAULT_GMCP_MODULE_VERSION;
+            m_outputs.onGmcpModuleEnabled(mod.getType(), false);
         }
     }
 }
diff --git a/src/proxy/UserTelnet.h b/src/proxy/UserTelnet.h
index 8cf7f4fbd..2692e5ea5 100644
--- a/src/proxy/UserTelnet.h
+++ b/src/proxy/UserTelnet.h
@@ -29,6 +29,10 @@ struct NODISCARD UserTelnetOutputs
     {
         virt_onRelayTermTypeFromUserToMud(bytes);
     }
+    void onGmcpModuleEnabled(const GmcpModuleTypeEnum type, const bool enabled)
+    {
+        virt_onGmcpModuleEnabled(type, enabled);
+    }
 
 private:
     virtual void virt_onAnalyzeUserStream(const RawBytes &, bool) = 0;
@@ -36,6 +40,7 @@ struct NODISCARD UserTelnetOutputs
     virtual void virt_onRelayGmcpFromUserToMud(const GmcpMessage &) = 0;
     virtual void virt_onRelayNawsFromUserToMud(int, int) = 0;
     virtual void virt_onRelayTermTypeFromUserToMud(const TelnetTermTypeBytes &) = 0;
+    virtual void virt_onGmcpModuleEnabled(GmcpModuleTypeEnum, bool) = 0;
 };
 
 class NODISCARD UserTelnet final : public AbstractTelnet
diff --git a/src/proxy/proxy.cpp b/src/proxy/proxy.cpp
index 78a62f3bd..d78756c47 100644
--- a/src/proxy/proxy.cpp
+++ b/src/proxy/proxy.cpp
@@ -41,11 +41,14 @@
 #include <tuple>
 
 #include <QByteArray>
+#include <QJsonDocument>
+#include <QJsonObject>
 #include <QMessageLogContext>
 #include <QObject>
 #include <QScopedPointer>
 #include <QSslSocket>
 #include <QTcpSocket>
+#include <QTimer>
 
 using mmqt::makeQPointer;
 
@@ -177,6 +180,8 @@ Proxy::~Proxy()
     sendNewlineToUser();
     sendStatusToUser("MMapper proxy is shutting down.");
 
+    stopClockBroadcaster();
+
     {
         qDebug() << "disconnecting mud socket...";
         getMudSocket().disconnectFromHost();
@@ -408,6 +413,16 @@ void Proxy::allocUserTelnet()
             // forwarded (to mud)
             getMudTelnet().onRelayTermType(bytes);
         }
+        void virt_onGmcpModuleEnabled(const GmcpModuleTypeEnum type, const bool enabled) final
+        {
+            if (type == GmcpModuleTypeEnum::MUME_TIME) {
+                if (enabled) {
+                    getProxy().startClockBroadcaster();
+                } else {
+                    getProxy().stopClockBroadcaster();
+                }
+            }
+        }
     };
 
     auto &pipe = getPipeline();
@@ -884,6 +899,143 @@ void Proxy::gmcpToUser(const GmcpMessage &msg)
     getUserTelnet().onGmcpToUser(msg);
 }
 
+namespace {
+
+NODISCARD constexpr const char *toJsonString(const MumeClockPrecisionEnum precision)
+{
+    switch (precision) {
+    case MumeClockPrecisionEnum::UNSET: return "unset";
+    case MumeClockPrecisionEnum::DAY: return "day";
+    case MumeClockPrecisionEnum::HOUR: return "hour";
+    case MumeClockPrecisionEnum::MINUTE: return "minute";
+    }
+    return "unknown";
+}
+
+NODISCARD constexpr const char *toJsonString(const MumeSeasonEnum season)
+{
+    switch (season) {
+    case MumeSeasonEnum::WINTER: return "winter";
+    case MumeSeasonEnum::SPRING: return "spring";
+    case MumeSeasonEnum::SUMMER: return "summer";
+    case MumeSeasonEnum::AUTUMN: return "autumn";
+    case MumeSeasonEnum::UNKNOWN: return "unknown";
+    }
+    return "unknown";
+}
+
+NODISCARD constexpr const char *toJsonString(const MumeTimeEnum time)
+{
+    switch (time) {
+    case MumeTimeEnum::DAWN: return "dawn";
+    case MumeTimeEnum::DAY: return "day";
+    case MumeTimeEnum::DUSK: return "dusk";
+    case MumeTimeEnum::NIGHT: return "night";
+    case MumeTimeEnum::UNKNOWN: return "unknown";
+    }
+    return "unknown";
+}
+
+NODISCARD constexpr const char *toJsonString(const MumeMoonPhaseEnum phase)
+{
+    switch (phase) {
+    case MumeMoonPhaseEnum::NEW_MOON: return "new_moon";
+    case MumeMoonPhaseEnum::WAXING_CRESCENT: return "waxing_crescent";
+    case MumeMoonPhaseEnum::FIRST_QUARTER: return "first_quarter";
+    case MumeMoonPhaseEnum::WAXING_GIBBOUS: return "waxing_gibbous";
+    case MumeMoonPhaseEnum::FULL_MOON: return "full_moon";
+    case MumeMoonPhaseEnum::WANING_GIBBOUS: return "waning_gibbous";
+    case MumeMoonPhaseEnum::THIRD_QUARTER: return "third_quarter";
+    case MumeMoonPhaseEnum::WANING_CRESCENT: return "waning_crescent";
+    case MumeMoonPhaseEnum::UNKNOWN: return "unknown";
+    }
+    return "unknown";
+}
+
+NODISCARD constexpr const char *toJsonString(const MumeMoonVisibilityEnum visibility)
+{
+    switch (visibility) {
+    case MumeMoonVisibilityEnum::BRIGHT: return "bright";
+    case MumeMoonVisibilityEnum::DIM: return "dim";
+    case MumeMoonVisibilityEnum::INVISIBLE: return "invisible";
+    case MumeMoonVisibilityEnum::UNKNOWN: return "unknown";
+    }
+    return "unknown";
+}
+
+} // namespace
+
+void Proxy::startClockBroadcaster()
+{
+    const auto &config = getConfig();
+
+    if (!config.mumeClock.gmcpBroadcast
+        || !isUserGmcpModuleEnabled(GmcpModuleTypeEnum::MUME_TIME)) {
+        stopClockBroadcaster();
+        return;
+    }
+
+    if (m_clockBroadcastTimer == nullptr) {
+        m_clockBroadcastTimer = new QTimer(this);
+        QObject::connect(m_clockBroadcastTimer, &QTimer::timeout, this, &Proxy::broadcastClockInfo);
+    }
+
+    // Clamp interval to a sane range to prevent tight timer loops
+    static constexpr int MIN_INTERVAL_MS = 500;
+    static constexpr int MAX_INTERVAL_MS = 60000;
+    const int interval = std::clamp(config.mumeClock.gmcpBroadcastInterval,
+                                    MIN_INTERVAL_MS,
+                                    MAX_INTERVAL_MS);
+    m_clockBroadcastTimer->setInterval(interval);
+    m_clockBroadcastTimer->start();
+
+    // Send initial update immediately
+    broadcastClockInfo();
+}
+
+void Proxy::stopClockBroadcaster()
+{
+    if (m_clockBroadcastTimer != nullptr && m_clockBroadcastTimer->isActive()) {
+        m_clockBroadcastTimer->stop();
+    }
+}
+
+void Proxy::broadcastClockInfo()
+{
+    if (!getConfig().mumeClock.gmcpBroadcast
+        || !isUserGmcpModuleEnabled(GmcpModuleTypeEnum::MUME_TIME)) {
+        return;
+    }
+
+    const MumeMoment moment = m_mumeClock.getMumeMoment();
+    const auto precision = m_mumeClock.getPrecision();
+    const auto [dawnHour, duskHour] = MumeClock::getDawnDusk(moment.month);
+
+    QJsonObject json;
+    json["year"] = moment.year;
+    json["month"] = moment.month;
+    json["day"] = moment.day;
+    json["hour"] = moment.hour;
+    json["minute"] = moment.minute;
+
+    json["precision"] = toJsonString(precision);
+    json["season"] = toJsonString(moment.toSeason());
+    json["timeOfDay"] = toJsonString(moment.toTimeOfDay());
+    json["moonPhase"] = toJsonString(moment.moonPhase());
+    json["moonVisibility"] = toJsonString(moment.moonVisibility());
+
+    json["moonLevel"] = moment.moonLevel();
+    json["dawnHour"] = dawnHour;
+    json["duskHour"] = duskHour;
+    json["syncEpoch"] = static_cast<qint64>(m_mumeClock.getLastSyncEpoch());
+
+    const QJsonDocument doc(json);
+    const QString jsonString = QString::fromUtf8(doc.toJson(QJsonDocument::Compact));
+
+    const GmcpMessage msg(GmcpMessageTypeEnum::MUME_TIME_INFO, GmcpJson{jsonString.toStdString()});
+    gmcpToUser(msg);
+}
+
 void Proxy::sendToMud(const QString &s)
 {
     // REVISIT: this bypasses game observer, but it also appears to be unused.
diff --git a/src/proxy/proxy.h b/src/proxy/proxy.h
index 3bb78a08f..11213cb54 100644
--- a/src/proxy/proxy.h
+++ b/src/proxy/proxy.h
@@ -153,6 +153,9 @@ class NODISCARD_QOBJECT Proxy final : public QObject
     // it outlives this object when the connection closes.
     QPointer<RemoteEdit> m_remoteEdit;
 
+    // Clock GMCP broadcaster
+    QTimer *m_clockBroadcastTimer = nullptr;
+
     enum class NODISCARD ServerStateEnum {
         Initialized,
         Offline,
@@ -227,6 +230,11 @@ class NODISCARD_QOBJECT Proxy final : public QObject
     void gmcpToMud(const GmcpMessage &msg);
     void gmcpToUser(const GmcpMessage &msg);
 
+private:
+    void startClockBroadcaster();
+    void stopClockBroadcaster();
+    void broadcastClockInfo();
+
 private:
     void sendToMud(const QString &s);
     void sendToUser(SendToUserSourceEnum source, const QString &ba);