diff --git a/src/dbus/applicationmanager1service.cpp b/src/dbus/applicationmanager1service.cpp
index 5951ae4..7c1bb83 100644
--- a/src/dbus/applicationmanager1service.cpp
+++ b/src/dbus/applicationmanager1service.cpp
@@ -187,10 +187,6 @@ void ApplicationManager1Service::initService(QDBusConnection &connection) noexce
 
 void ApplicationManager1Service::addInstanceToApplication(const QString &unitName, const QDBusObjectPath &systemdUnitPath)
 {
-    if (!isApplication(systemdUnitPath)) {
-        return;
-    }
-
     auto info = processUnitName(unitName);
     auto appId = std::move(info.applicationID);
     auto launcher = std::move(info.Launcher);
@@ -199,6 +195,9 @@ void ApplicationManager1Service::addInstanceToApplication(const QString &unitNam
     if (appId.isEmpty()) {
         return;
     }
+    if (instanceId.isEmpty()) {
+        instanceId = QUuid::createUuid().toString(QUuid::Id128);
+    }
 
     auto appIt = std::find_if(m_applicationList.cbegin(),
                               m_applicationList.cend(),
@@ -220,10 +219,6 @@ void ApplicationManager1Service::addInstanceToApplication(const QString &unitNam
 
 void ApplicationManager1Service::removeInstanceFromApplication(const QString &unitName, const QDBusObjectPath &systemdUnitPath)
 {
-    if (!isApplication(systemdUnitPath)) {
-        return;
-    }
-
     auto info = processUnitName(unitName);
     auto appId = std::move(info.applicationID);
     auto launcher = std::move(info.Launcher);
@@ -316,9 +311,6 @@ void ApplicationManager1Service::scanInstances() noexcept
     QList<SystemdUnitDBusMessage> units;
     v.value<QDBusArgument>() >> units;
     for (const auto &unit : units) {
-        if (!isApplication(unit.objectPath)) {
-            continue;
-        }
         if (unit.subState == "running") {
             this->addInstanceToApplication(unit.name, unit.objectPath);
         }
@@ -567,10 +559,16 @@ QString ApplicationManager1Service::Identify(const QDBusUnixFileDescriptor &pidf
         return {};
     }
 
-    auto instancePath = (*app)->findInstance(ret.InstanceId);
-
-    if (auto path = instancePath.path(); path.isEmpty()) {
-        sendErrorReply(QDBusError::Failed, "can't find instance:" % path);
+    QDBusObjectPath instancePath;
+    const auto &instances = (*app)->instances();
+    if (ret.InstanceId.isEmpty() && instances.size() == 1) {
+        // Maybe a dbus systemd service
+        instancePath = instances.constFirst();
+    } else {
+        instancePath = (*app)->findInstance(ret.InstanceId);
+    }
+    if (instancePath.path().isEmpty()) {
+        sendErrorReply(QDBusError::Failed, "can't find instance:" % ret.InstanceId);
         return {};
     }
 
diff --git a/src/global.h b/src/global.h
index 0937041..0b86caa 100644
--- a/src/global.h
+++ b/src/global.h
@@ -481,11 +481,6 @@ inline QString getCurrentDesktop()
     return desktops.first();
 }
 
-inline bool isApplication(const QDBusObjectPath &path)
-{
-    return path.path().split('/').last().startsWith("app");
-}
-
 struct unitInfo
 {
     QString applicationID;
@@ -503,8 +498,10 @@ inline unitInfo processUnitName(const QString &unitName)
 
     decltype(auto) appPrefix = u8"app-";
     if (!unitName.startsWith(appPrefix)) {
-        qDebug() << "this unit " << unitName << "isn't an app unit.";
-        return {};
+        // If not started by application manager, just remove suffix and take name as app id.
+        auto lastDotIndex = unitName.lastIndexOf('.');
+        applicationId = unitName.sliced(0, lastDotIndex);
+        return {unescapeApplicationId(applicationId), std::move(launcher), std::move(instanceId)};
     }
 
     auto unit = unitName.sliced(sizeof(appPrefix) - 1);
@@ -540,10 +537,6 @@ inline unitInfo processUnitName(const QString &unitName)
         return {};
     }
 
-    if (instanceId.isEmpty()) {
-        instanceId = QUuid::createUuid().toString(QUuid::Id128);
-    }
-
     return {unescapeApplicationId(applicationId), std::move(launcher), std::move(instanceId)};
 }
 
diff --git a/src/systemdsignaldispatcher.cpp b/src/systemdsignaldispatcher.cpp
index df729c8..d3c36d0 100644
--- a/src/systemdsignaldispatcher.cpp
+++ b/src/systemdsignaldispatcher.cpp
@@ -54,18 +54,10 @@ void SystemdSignalDispatcher::onPropertiesChanged(QString interface, QVariantMap
 
 void SystemdSignalDispatcher::onUnitNew(QString unitName, QDBusObjectPath systemdUnitPath)
 {
-    if (!unitName.startsWith("app-")) {
-        return;
-    }
-
     emit SystemdUnitNew(unitName, systemdUnitPath);
 }
 
 void SystemdSignalDispatcher::onUnitRemoved(QString unitName, QDBusObjectPath systemdUnitPath)
 {
-    if (!unitName.startsWith("app-")) {
-        return;
-    }
-
     emit SystemdUnitRemoved(unitName, systemdUnitPath);
 }