diff --git a/autotests/kwindowinfox11test.cpp b/autotests/kwindowinfox11test.cpp
--- a/autotests/kwindowinfox11test.cpp
+++ b/autotests/kwindowinfox11test.cpp
@@ -415,6 +415,7 @@
     QTest::newRow("ComboBox")           << NET::ComboBoxMask     << NET::ComboBox     << NET::ComboBox;
     QTest::newRow("DNDIcon")            << NET::DNDIconMask      << NET::DNDIcon      << NET::DNDIcon;
     QTest::newRow("OnScreenDisplay")    << NET::OnScreenDisplayMask << NET::OnScreenDisplay << NET::OnScreenDisplay;
+    QTest::newRow("CriticalNotification") << NET::CriticalNotificationMask << NET::CriticalNotification << NET::CriticalNotification;
 
     // incorrect masks
     QTest::newRow("desktop-unknown")      << NET::NormalMask << NET::Desktop      << NET::Unknown;
@@ -433,6 +434,7 @@
     QTest::newRow("ComboBox-unknown")     << NET::NormalMask << NET::ComboBox     << NET::Unknown;
     QTest::newRow("DNDIcon-unknown")      << NET::NormalMask << NET::DNDIcon      << NET::Unknown;
     QTest::newRow("OnScreenDisplay-unknown") << NET::NormalMask << NET::OnScreenDisplay << NET::Unknown;
+    QTest::newRow("CriticalNotification-unknown") << NET::NormalMask << NET::CriticalNotification << NET::Unknown;
 }
 
 void KWindowInfoX11Test::testWindowType()
diff --git a/autotests/netrootinfotestwm.cpp b/autotests/netrootinfotestwm.cpp
--- a/autotests/netrootinfotestwm.cpp
+++ b/autotests/netrootinfotestwm.cpp
@@ -216,7 +216,7 @@
     NETRootInfo rootInfo(connection(), m_supportWindow, s_wmName,
                          NET::WMAllProperties, NET::AllTypesMask, NET::States(~0u), NET::WM2AllProperties, NET::Actions(~0u));
     int count = 0;
-    for (int i = 0; i < 32; ++i) {
+    for (int i = 0; i < 33; ++i) {
         if (i == 12) {
             continue;
         }
diff --git a/autotests/netwininfotestclient.cpp b/autotests/netwininfotestclient.cpp
--- a/autotests/netwininfotestclient.cpp
+++ b/autotests/netwininfotestclient.cpp
@@ -601,6 +601,7 @@
     QTest::newRow("DNDIcon")      << NET::DNDIcon      << 1 << QByteArrayLiteral("_NET_WM_WINDOW_TYPE_DND")      << QByteArray();
     QTest::newRow("Normal")       << NET::Normal       << 1 << QByteArrayLiteral("_NET_WM_WINDOW_TYPE_NORMAL")   << QByteArray();
     QTest::newRow("OnScreenDisplay") << NET::OnScreenDisplay << 1 << QByteArrayLiteral("_KDE_NET_WM_WINDOW_TYPE_ON_SCREEN_DISPLAY") << QByteArray();
+    QTest::newRow("CriticalNotification") << NET::CriticalNotification << 1 << QByteArrayLiteral("_KDE_NET_WM_WINDOW_TYPE_CRITICAL_NOTIFICATION") << QByteArray();
 }
 
 void NetWinInfoTestClient::testWindowType()
diff --git a/src/netwm_def.h b/src/netwm_def.h
--- a/src/netwm_def.h
+++ b/src/netwm_def.h
@@ -378,7 +378,12 @@
             indicates an On Screen Display window (such as volume feedback)
             @since 5.6
         **/
-        OnScreenDisplay = 16 // NON STANDARD
+        OnScreenDisplay = 16, // NON STANDARD
+        /**
+            indicates a critical notification (such as battery is running out)
+            @since 5.58
+        **/
+        CriticalNotification = 17, // NON STANDARD
     };
 
     /**
@@ -403,6 +408,7 @@
         ComboBoxMask     = 1u << 14, ///< @see ComboBox
         DNDIconMask      = 1u << 15, ///< @see DNDIcon
         OnScreenDisplayMask = 1u << 16, ///< NON STANDARD @see OnScreenDisplay @since 5.6
+        CriticalNotificationMask = 1u << 17, ///< NON STANDARD @see CriticalNotification @since 5.58
         AllTypesMask     = 0U - 1 ///< All window types.
     };
     Q_DECLARE_FLAGS(WindowTypes, WindowTypeMask)
diff --git a/src/platforms/xcb/atoms_p.h b/src/platforms/xcb/atoms_p.h
--- a/src/platforms/xcb/atoms_p.h
+++ b/src/platforms/xcb/atoms_p.h
@@ -154,6 +154,7 @@
     ENUM(_KDE_NET_WM_WINDOW_TYPE_OVERRIDE),
     ENUM(_KDE_NET_WM_WINDOW_TYPE_TOPMENU),
     ENUM(_KDE_NET_WM_WINDOW_TYPE_ON_SCREEN_DISPLAY),
+    ENUM(_KDE_NET_WM_WINDOW_TYPE_CRITICAL_NOTIFICATION),
     ENUM(_KDE_NET_WM_TEMPORARY_RULES),
     ENUM(_NET_WM_FRAME_OVERLAP),
     // deprecated and naming convention violation
diff --git a/src/platforms/xcb/netwm.cpp b/src/platforms/xcb/netwm.cpp
--- a/src/platforms/xcb/netwm.cpp
+++ b/src/platforms/xcb/netwm.cpp
@@ -976,6 +976,9 @@
         if (p->windowTypes & OnScreenDisplayMask) {
             atoms[pnum++] = p->atom(_KDE_NET_WM_WINDOW_TYPE_ON_SCREEN_DISPLAY);
         }
+        if (p->windowTypes & CriticalNotificationMask) {
+            atoms[pnum++] = p->atom(_KDE_NET_WM_WINDOW_TYPE_CRITICAL_NOTIFICATION);
+        }
     }
 
     if (p->properties & WMState) {
@@ -1301,6 +1304,8 @@
         p->windowTypes |= TopMenuMask;
     } else if (atom == p->atom(_KDE_NET_WM_WINDOW_TYPE_ON_SCREEN_DISPLAY)) {
         p->windowTypes |= OnScreenDisplayMask;
+    } else if (atom == p->atom(_KDE_NET_WM_WINDOW_TYPE_CRITICAL_NOTIFICATION)) {
+        p->windowTypes |= CriticalNotificationMask;
     }
 
     else if (atom == p->atom(_NET_WM_STATE)) {
@@ -3219,6 +3224,12 @@
         len = 1;
         break;
 
+    case CriticalNotification:
+        data[0] = p->atom(_KDE_NET_WM_WINDOW_TYPE_CRITICAL_NOTIFICATION);
+        data[1] = p->atom(_NET_WM_WINDOW_TYPE_NOTIFICATION);
+        len = 1;
+        break;
+
     default:
     case Normal:
         data[0] = p->atom(_NET_WM_WINDOW_TYPE_NORMAL);
@@ -4246,6 +4257,10 @@
                 else if (type == p->atom(_KDE_NET_WM_WINDOW_TYPE_ON_SCREEN_DISPLAY)) {
                     p->types[pos++] = OnScreenDisplay;
                 }
+
+                else if (type == p->atom(_KDE_NET_WM_WINDOW_TYPE_CRITICAL_NOTIFICATION)) {
+                    p->types[pos++] = CriticalNotification;
+                }
             }
         }
     }
@@ -4633,6 +4648,7 @@
         CHECK_TYPE_MASK(ComboBox)
         CHECK_TYPE_MASK(DNDIcon)
         CHECK_TYPE_MASK(OnScreenDisplay)
+        CHECK_TYPE_MASK(CriticalNotification)
 #undef CHECK_TYPE_MASK
     default:
         break;