diff --git a/autotests/integration/tabbox_test.cpp b/autotests/integration/tabbox_test.cpp
--- a/autotests/integration/tabbox_test.cpp
+++ b/autotests/integration/tabbox_test.cpp
@@ -127,9 +127,7 @@
 
     // release alt
     kwinApp()->platform()->keyboardKeyReleased(KEY_LEFTALT, timestamp++);
-    QEXPECT_FAIL("", "bug 368590", Continue);
     QCOMPARE(tabboxClosedSpy.count(), 1);
-    QEXPECT_FAIL("", "bug 368590", Continue);
     QCOMPARE(TabBox::TabBox::self()->isGrabbed(), false);
 
     // release caps lock
diff --git a/input.cpp b/input.cpp
--- a/input.cpp
+++ b/input.cpp
@@ -745,8 +745,11 @@
             return false;
         }
         waylandServer()->seat()->setFocusedKeyboardSurface(nullptr);
-        if (event->type() == QEvent::KeyPress)
+        if (event->type() == QEvent::KeyPress) {
             TabBox::TabBox::self()->keyPress(event->modifiers() | event->key());
+        } else if (input()->keyboard()->xkb()->modifiersRelevantForGlobalShortcuts() == Qt::NoModifier) {
+            TabBox::TabBox::self()->modifiersReleased();
+        }
         return true;
     }
     bool wheelEvent(QWheelEvent *event) override {
diff --git a/tabbox/tabbox.h b/tabbox/tabbox.h
--- a/tabbox/tabbox.h
+++ b/tabbox/tabbox.h
@@ -181,6 +181,7 @@
     int previousDesktopStatic(int iDesktop) const;
     void keyPress(int key);
     void keyRelease(const xcb_key_release_event_t *ev);
+    void modifiersReleased();
 
     bool forcedGlobalMouseGrab() const {
         return m_forcedGlobalMouseGrab;
@@ -243,7 +244,6 @@
 private Q_SLOTS:
     void reconfigure();
     void globalShortcutChanged(QAction *action, const QKeySequence &seq);
-    void modifiersChanged(Qt::KeyboardModifiers mods);
 
 private:
     TabBoxMode m_tabBoxMode;
diff --git a/tabbox/tabbox.cpp b/tabbox/tabbox.cpp
--- a/tabbox/tabbox.cpp
+++ b/tabbox/tabbox.cpp
@@ -36,6 +36,7 @@
 #include "client.h"
 #include "effects.h"
 #include "input.h"
+#include "keyboard_input.h"
 #include "focuschain.h"
 #include "screenedge.h"
 #include "screens.h"
@@ -498,8 +499,6 @@
     m_tabBoxMode = TabBoxDesktopMode; // init variables
     connect(&m_delayedShowTimer, SIGNAL(timeout()), this, SLOT(show()));
     connect(Workspace::self(), SIGNAL(configChanged()), this, SLOT(reconfigure()));
-
-    connect(input(), &InputRedirection::keyboardModifiersChanged, this, &TabBox::modifiersChanged);
 }
 
 TabBox::~TabBox()
@@ -1076,7 +1075,7 @@
 static bool areModKeysDepressedWayland(const QKeySequence &seq)
 {
     const int mod = seq[seq.count()-1] & Qt::KeyboardModifierMask;
-    const Qt::KeyboardModifiers mods = input()->keyboardModifiers();
+    const Qt::KeyboardModifiers mods = input()->keyboard()->xkb()->modifiersRelevantForGlobalShortcuts();
     if ((mod & Qt::SHIFT) && mods.testFlag(Qt::ShiftModifier)) {
         return true;
     }
@@ -1570,9 +1569,9 @@
     }
 }
 
-void TabBox::modifiersChanged(Qt::KeyboardModifiers mods)
+void TabBox::modifiersReleased()
 {
-    if (m_noModifierGrab || !(!mods)) {
+    if (m_noModifierGrab) {
         return;
     }
     if (m_tabGrab) {