diff --git a/Changelog b/Changelog
index 204b9bee..751d3068 100644
--- a/Changelog
+++ b/Changelog
@@ -3,6 +3,7 @@
   - Added static DockWidgetBase::byName() (#126)
   - SOURCE-COMPAT-BREAK: The enum KDDockWidgets::AddingOption has been renamed to
     KDDockWidgets::InitialVisibilityOption
+  - You can now pass a preferred initial size to MainWindow::addDockWidget() (#95)
 
 * v1.2.1 (unreleased)
   - Support for resizing dock widgets when they are in overlay/popup mode (autohide/sidebar feature)
diff --git a/examples/minimal/main.cpp b/examples/minimal/main.cpp
index 2d99c5dd..dd0ad3bf 100644
--- a/examples/minimal/main.cpp
+++ b/examples/minimal/main.cpp
@@ -62,6 +62,10 @@ int main(int argc, char **argv)
                                 QStringLiteral(":/assets/KDAB_bubble_fulcolor.png"));
     dock4->setWidget(widget4);
 
+    auto dock5 = new KDDockWidgets::DockWidget(QStringLiteral("MyDock5"));
+    auto widget5 = new MyWidget(QStringLiteral(":/assets/base.png"),
+                                QStringLiteral(":/assets/KDAB_bubble_fulcolor.png"));
+    dock5->setWidget(widget5);
 
     // 3. Add them to the main window
     mainWindow.addDockWidget(dock1, KDDockWidgets::Location_OnLeft);
@@ -70,8 +74,13 @@ int main(int argc, char **argv)
     // 4. Add dock3 to the right of dock2
     mainWindow.addDockWidget(dock3, KDDockWidgets::Location_OnRight, dock2);
 
-    // 5. dock4 will be its own top level (floating window)
-    dock4->show();
+    // 5. dock4 is docked at the bottom, with 200px height
+    const QSize preferredSize(QSize(/*ignored*/0, 200));
+    mainWindow.addDockWidget(dock4, KDDockWidgets::Location_OnBottom, nullptr, preferredSize);
+
+
+    // 5. dock5 will be its own top level (floating window)
+    dock5->show();
 
     return app.exec();
 }
diff --git a/src/KDDockWidgets.h b/src/KDDockWidgets.h
index 5778d9b1..4a37aff8 100644
--- a/src/KDDockWidgets.h
+++ b/src/KDDockWidgets.h
@@ -88,18 +88,27 @@ namespace KDDockWidgets
         InitialOption(InitialVisibilityOption v)
             : visibility(v) {}
 
-        /*InitialOption(QSize size)
+        InitialOption(QSize size)
             : preferredSize(size) {}
 
         InitialOption(InitialVisibilityOption v, QSize size)
             : visibility(v)
             , preferredSize(size)
-        {}*/
+        {}
 
         bool startsHidden() const {
             return visibility == InitialVisibilityOption::StartHidden;
         }
 
+        int preferredLength(Qt::Orientation o) const {
+            return o == Qt::Horizontal ? preferredSize.width()
+                                       : preferredSize.height();
+        }
+
+        bool hasPreferredLength(Qt::Orientation o) const {
+            return preferredLength(o) > 0;
+        }
+
         /**
          * @brief Allows a dock widget to be docked as hidden.
          *
@@ -117,7 +126,7 @@ namespace KDDockWidgets
          * dock widget to the left then only the preferred width will be taken into account, as the
          * height will simply fill the whole layout.
          */
-        //const QSize preferredSize; not yet done.
+        const QSize preferredSize;
 
     private:
         friend class Layouting::Item;
diff --git a/src/private/multisplitter/Item.cpp b/src/private/multisplitter/Item.cpp
index b9fad5b4..af580121 100644
--- a/src/private/multisplitter/Item.cpp
+++ b/src/private/multisplitter/Item.cpp
@@ -3603,23 +3603,28 @@ void SizingInfo::fromVariantMap(const QVariantMap &map)
 int ItemContainer::Private::defaultLengthFor(Item *item, InitialOption option) const
 {
     int result = 0;
-    switch (option.sizeMode) {
-    case DefaultSizeMode::None:
-        break;
-    case DefaultSizeMode::Fair: {
-        const int numVisibleChildren = q->numVisibleChildren() + 1; // +1 so it counts with @p item too, which we're adding
-        const int usableLength = q->length() - (Item::separatorThickness*(numVisibleChildren - 1));
-        result = usableLength / numVisibleChildren;
-        break;
-    }
-    case DefaultSizeMode::FairButFloor: {
-        int length = defaultLengthFor(item, DefaultSizeMode::Fair);
-        result = qMin(length, item->length(m_orientation));
-        break;
-    }
-    case DefaultSizeMode::ItemSize:
-        result = item->length(m_orientation);
-        break;
+
+    if (option.hasPreferredLength(m_orientation) && option.sizeMode != DefaultSizeMode::None) {
+        result = option.preferredLength(m_orientation);
+    } else {
+        switch (option.sizeMode) {
+        case DefaultSizeMode::None:
+            break;
+        case DefaultSizeMode::Fair: {
+            const int numVisibleChildren = q->numVisibleChildren() + 1; // +1 so it counts with @p item too, which we're adding
+            const int usableLength = q->length() - (Item::separatorThickness*(numVisibleChildren - 1));
+            result = usableLength / numVisibleChildren;
+            break;
+        }
+        case DefaultSizeMode::FairButFloor: {
+            int length = defaultLengthFor(item, DefaultSizeMode::Fair);
+            result = qMin(length, item->length(m_orientation));
+            break;
+        }
+        case DefaultSizeMode::ItemSize:
+            result = item->length(m_orientation);
+            break;
+        }
     }
 
     result = qMax(item->minLength(m_orientation), result); // bound with max-size too
diff --git a/tests/tst_docks.cpp b/tests/tst_docks.cpp
index b03d5058..7344f39c 100644
--- a/tests/tst_docks.cpp
+++ b/tests/tst_docks.cpp
@@ -161,6 +161,7 @@ private Q_SLOTS:
     void tst_placeholderDisappearsOnReadd();
     void tst_placeholdersAreRemovedProperly();
     void tst_floatMaintainsSize();
+    void tst_preferredInitialSize();
 
     void tst_crash2_data();
     void tst_crash2();
@@ -2245,6 +2246,19 @@ void TestDocks::tst_floatMaintainsSize()
     delete dw2->window();
 }
 
+void TestDocks::tst_preferredInitialSize()
+{
+    EnsureTopLevelsDeleted e;
+    auto dw1 = new DockWidgetType("1");
+    auto dw2 = new DockWidgetType("2");
+    auto m = createMainWindow(QSize(1200, 1200), MainWindowOption_None);
+
+    m->addDockWidget(dw1, Location_OnTop);
+    m->addDockWidget(dw2, Location_OnBottom, nullptr, QSize(0, 200));
+
+    QCOMPARE(dw2->frame()->height(), 200);
+}
+
 void TestDocks::tst_crash2_data()
 {
     QTest::addColumn<bool>("show");