diff --git a/src/dbus/qdbusconnection.cpp b/src/dbus/qdbusconnection.cpp
index f6918b70b02..14c9ebe6205 100644
--- a/src/dbus/qdbusconnection.cpp
+++ b/src/dbus/qdbusconnection.cpp
@@ -873,7 +873,9 @@ QString QDBusConnection::name() const
 */
 QDBusConnection::ConnectionCapabilities QDBusConnection::connectionCapabilities() const
 {
-    return d ? d->connectionCapabilities() : ConnectionCapabilities();
+    if (!d)
+        return {};
+    return d->connectionCapabilities() & ~QDBusConnectionPrivate::InternalCapabilitiesMask;
 }
 
 /*!
diff --git a/src/dbus/qdbusconnection_p.h b/src/dbus/qdbusconnection_p.h
index 53e68748186..5cb175c1cdc 100644
--- a/src/dbus/qdbusconnection_p.h
+++ b/src/dbus/qdbusconnection_p.h
@@ -276,11 +276,18 @@ signals:
     void callWithCallbackFailed(const QDBusError &error, const QDBusMessage &message);
 
 public:
+    static constexpr QDBusConnection::ConnectionCapabilities ConnectionIsBus =
+            QDBusConnection::ConnectionCapabilities::fromInt(0x8000'0000);
+    static constexpr QDBusConnection::ConnectionCapabilities InternalCapabilitiesMask = ConnectionIsBus;
+
     QAtomicInt ref;
     QAtomicInt capabilities;
     QDBusConnection::ConnectionCapabilities connectionCapabilities() const
     {
-        return (QDBusConnection::ConnectionCapabilities)capabilities.loadRelaxed();
+        uint capa = capabilities.loadRelaxed();
+        if (mode == ClientMode)
+            capa |= ConnectionIsBus;
+        return QDBusConnection::ConnectionCapabilities(capa);
     }
     QString name;               // this connection's name
     QString baseService;        // this connection's base service
diff --git a/src/dbus/qdbusmessage.cpp b/src/dbus/qdbusmessage.cpp
index 6ef762f2257..b89ab6a3988 100644
--- a/src/dbus/qdbusmessage.cpp
+++ b/src/dbus/qdbusmessage.cpp
@@ -109,7 +109,10 @@ DBusMessage *QDBusMessagePrivate::toDBusMessage(const QDBusMessage &message, QDB
     case QDBusMessage::MethodCallMessage:
         // only service and interface can be empty -> path and name must not be empty
         if (!d_ptr->parametersValidated) {
-            if (!QDBusUtil::checkBusName(d_ptr->service, QDBusUtil::EmptyAllowed, error))
+            using namespace QDBusUtil;
+            AllowEmptyFlag serviceCheckMode = capabilities & QDBusConnectionPrivate::ConnectionIsBus
+                    ? EmptyNotAllowed : EmptyAllowed;
+            if (!checkBusName(d_ptr->service, serviceCheckMode, error))
                 return nullptr;
             if (!QDBusUtil::checkObjectPath(d_ptr->path, QDBusUtil::EmptyNotAllowed, error))
                 return nullptr;
@@ -146,7 +149,7 @@ DBusMessage *QDBusMessagePrivate::toDBusMessage(const QDBusMessage &message, QDB
         }
         break;
     case QDBusMessage::SignalMessage:
-        // only the service name can be empty here
+        // only the service name can be empty here (even for bus connections)
         if (!d_ptr->parametersValidated) {
             if (!QDBusUtil::checkBusName(d_ptr->service, QDBusUtil::EmptyAllowed, error))
                 return nullptr;
diff --git a/tests/auto/dbus/qdbusmarshall/tst_qdbusmarshall.cpp b/tests/auto/dbus/qdbusmarshall/tst_qdbusmarshall.cpp
index 82dc9059e02..ea515536e6e 100644
--- a/tests/auto/dbus/qdbusmarshall/tst_qdbusmarshall.cpp
+++ b/tests/auto/dbus/qdbusmarshall/tst_qdbusmarshall.cpp
@@ -933,10 +933,9 @@ void tst_QDBusMarshall::sendCallErrors_data()
     QTest::addColumn<QString>("errorMsg");
     QTest::addColumn<QString>("ignoreMsg");
 
-    // this error comes from the bus server
     QTest::newRow("empty-service") << "" << objectPath << interfaceName << "ping" << QVariantList()
-            << "org.freedesktop.DBus.Error.UnknownMethod"
-            << "Method \"ping\" with signature \"\" on interface \"org.qtproject.autotests.qpong\" doesn't exist\n" << (const char*)0;
+            << "org.qtproject.QtDBus.Error.InvalidService"
+            << "Service name cannot be empty" << "";
 
     QTest::newRow("invalid-service-single-label") << "service" << objectPath << interfaceName << "ping" << QVariantList()
             << "org.qtproject.QtDBus.Error.InvalidService"