diff --git a/src/widgets/widgets/qtoolbar.cpp b/src/widgets/widgets/qtoolbar.cpp
index 0d386a4378a..b8b462b03f8 100644
--- a/src/widgets/widgets/qtoolbar.cpp
+++ b/src/widgets/widgets/qtoolbar.cpp
@@ -912,8 +912,13 @@ void QToolBar::changeEvent(QEvent *event)
         break;
     case QEvent::StyleChange:
         d->layout->invalidate();
-        if (!d->explicitIconSize)
-            setIconSize(QSize());
+        if (!d->explicitIconSize) {
+            QStyleOptionToolBar opt;
+            initStyleOption(&opt);
+            const int metric = style()->pixelMetric(QStyle::PM_ToolBarIconSize, &opt, this);
+            setIconSize({metric, metric});
+            d->explicitIconSize = false;
+        }
         d->layout->updateMarginAndSpacing();
         break;
     case QEvent::LayoutDirectionChange:
diff --git a/tests/auto/widgets/widgets/qtoolbar/tst_qtoolbar.cpp b/tests/auto/widgets/widgets/qtoolbar/tst_qtoolbar.cpp
index 8b8c74b1e7d..6c3f7ccb197 100644
--- a/tests/auto/widgets/widgets/qtoolbar/tst_qtoolbar.cpp
+++ b/tests/auto/widgets/widgets/qtoolbar/tst_qtoolbar.cpp
@@ -62,6 +62,7 @@ private slots:
     void task197996_visibility();
 
     void extraCpuConsumption(); // QTBUG-54676
+    void iconSizeStyleSheet();
 };
 
 
@@ -1164,5 +1165,45 @@ void tst_QToolBar::extraCpuConsumption()
     QCOMPARE(eventCounter->hideEventsCount(), uint(1));
 }
 
+void tst_QToolBar::iconSizeStyleSheet()
+{
+    auto resetStyleSheet = qScopeGuard([]{
+        qApp->setStyleSheet({});
+    });
+
+    QMainWindow mw;
+    QToolBar tb1;
+    QToolBar tb2;
+    mw.addToolBar(&tb1);
+    mw.addToolBar(&tb2);
+
+    const QString styleSheet = "QToolBar { icon-size: %1px; }";
+
+    const int targetIconSize1 = 48;
+    const int targetIconSize2 = 58;
+    const int targetIconSize3 = 68;
+    const int targetIconSize4 = 78;
+
+    // Set iconSize via stylesheet using icon-size property first time
+    qApp->setStyleSheet(styleSheet.arg(targetIconSize1));
+    QTRY_COMPARE(tb1.iconSize(), QSize(targetIconSize1, targetIconSize1));
+    QTRY_COMPARE(tb2.iconSize(), QSize(targetIconSize1, targetIconSize1));
+
+    qApp->setStyleSheet(styleSheet.arg(targetIconSize2));
+    QTRY_COMPARE(tb1.iconSize(), QSize(targetIconSize2, targetIconSize2));
+    QTRY_COMPARE(tb2.iconSize(), QSize(targetIconSize2, targetIconSize2));
+
+    // Set tb2's icon size explicitly via setIconSize()
+    tb2.setIconSize(QSize(targetIconSize3, targetIconSize3));
+    QCOMPARE(tb1.iconSize(), QSize(targetIconSize2, targetIconSize2));
+    QCOMPARE(tb2.iconSize(), QSize(targetIconSize3, targetIconSize3));
+
+    // Set iconSize via stylesheet using icon-size property after setting using setIconSize()
+    qApp->setStyleSheet(styleSheet.arg(targetIconSize4));
+    // setIconSize has precedence over iconSize set via stylesheet using icon-size property
+    QTRY_COMPARE(tb1.iconSize(), QSize(targetIconSize4, targetIconSize4));
+    QCOMPARE(tb2.iconSize(), QSize(targetIconSize3, targetIconSize3));
+}
+
 QTEST_MAIN(tst_QToolBar)
 #include "tst_qtoolbar.moc"