diff --git a/src/libcalamaresui/Branding.cpp b/src/libcalamaresui/Branding.cpp
index 7f8e8c343..ecba9c27d 100644
--- a/src/libcalamaresui/Branding.cpp
+++ b/src/libcalamaresui/Branding.cpp
@@ -21,6 +21,7 @@
 
 #include "GlobalStorage.h"
 #include "utils/CalamaresUtils.h"
+#include "utils/CalamaresUtilsGui.h"
 #include "utils/ImageRegistry.h"
 #include "utils/Logger.h"
 #include "utils/NamedEnum.h"
@@ -77,6 +78,17 @@ const QStringList Branding::s_styleEntryStrings =
     "sidebarTextHighlight"
 };
 
+static const NamedEnumTable<Branding::WindowDimensionUnit>&
+windowDimensions()
+{
+    using Unit = Branding::WindowDimensionUnit;
+    static const NamedEnumTable<Unit> names{
+        {"px", Unit::Pixies},
+        {"em", Unit::Fonties}
+    };
+
+    return names;
+}
 
 Branding::Branding( const QString& brandingFilePath,
                     QObject* parent )
@@ -287,23 +299,47 @@ Branding::setGlobals( GlobalStorage* globalStorage ) const
     globalStorage->insert( "branding", brandingMap );
 }
 
+bool
+Branding::WindowDimension::isValid() const
+{
+    return ( unit() != none ) && ( value() > 0 );
+}
 
 void
 Branding::initSimpleSettings( const YAML::Node& doc )
 {
-    static const NamedEnumTable< WindowExpansion > weNames{
+    static const NamedEnumTable< WindowExpansion > expansionNames{
         { QStringLiteral( "normal" ), WindowExpansion::Normal },
         { QStringLiteral( "fullscreen" ), WindowExpansion::Fullscreen },
         { QStringLiteral( "noexpand" ), WindowExpansion::Fixed }
     };
+    static const NamedEnumTable< WindowDimensionUnit > dimensionNames{
+        { QStringLiteral( "px" ), WindowDimensionUnit::Pixies },
+        { QStringLiteral( "em" ), WindowDimensionUnit::Fonties }
+    };
 
     bool ok = false;
 
     m_welcomeStyleCalamares = doc[ "welcomeStyleCalamares" ].as< bool >( false );
     m_welcomeExpandingLogo = doc[ "welcomeExpandingLogo" ].as< bool >( true );
-    m_windowExpansion = weNames.find( QString::fromStdString( doc[ "windowExpanding" ].as< std::string >() ), ok );
+    m_windowExpansion = expansionNames.find( QString::fromStdString( doc[ "windowExpanding" ].as< std::string >() ), ok );
     if ( !ok )
-        cWarning() << "Branding module-setting *windowExpanding* interpreted as" << weNames.find( m_windowExpansion, ok );
+        cWarning() << "Branding module-setting *windowExpanding* interpreted as" << expansionNames.find( m_windowExpansion, ok );
+
+    QString windowSize = QString::fromStdString( doc[ "windowSize" ].as< std::string >() );
+    if ( !windowSize.isEmpty() )
+    {
+        auto l = windowSize.split( ',' );
+        if ( l.count() == 2 )
+        {
+            m_windowWidth = WindowDimension( dimensionNames, l[0] );
+            m_windowHeight = WindowDimension( dimensionNames, l[1] );
+        }
+    }
+    if ( !m_windowWidth.isValid() || m_windowWidth.value() < CalamaresUtils::windowMinimumWidth )
+        m_windowWidth = WindowDimension( CalamaresUtils::windowPreferredWidth, WindowDimensionUnit::Pixies );
+    if ( !m_windowHeight.isValid() || m_windowHeight.value() < CalamaresUtils::windowMinimumHeight )
+        m_windowHeight = WindowDimension( CalamaresUtils::windowPreferredHeight, WindowDimensionUnit::Pixies );
 }
 
 
diff --git a/src/libcalamaresui/Branding.h b/src/libcalamaresui/Branding.h
index 94136791c..611ce6c12 100644
--- a/src/libcalamaresui/Branding.h
+++ b/src/libcalamaresui/Branding.h
@@ -23,6 +23,8 @@
 #include "UiDllMacro.h"
 #include "Typedefs.h"
 
+#include "utils/NamedSuffix.h"
+
 #include <QObject>
 #include <QStringList>
 #include <QMap>
@@ -78,6 +80,18 @@ public:
 
     /** @brief Setting for how much the main window may expand. */
     enum class WindowExpansion { Normal, Fullscreen, Fixed } ;
+    /** @brief Setting for the main window size.
+     *
+     * The units are pixels (Pixies) or something-based-on-fontsize (Fonties), which
+     * we suffix as "em", e.g. "600px" or "32em".
+     */
+    enum class WindowDimensionUnit { None, Pixies, Fonties };
+    class WindowDimension : public NamedSuffix<WindowDimensionUnit, WindowDimensionUnit::None>
+    {
+    public:
+        using NamedSuffix::NamedSuffix;
+        bool isValid() const;
+    } ;
 
     static Branding* instance();
 
@@ -97,6 +111,10 @@ public:
 
     bool welcomeStyleCalamares() const { return m_welcomeStyleCalamares; }
     bool welcomeExpandingLogo() const { return m_welcomeExpandingLogo; }
+    QPair< WindowDimension, WindowDimension > windowSize() const
+    {
+        return QPair< WindowDimension, WindowDimension >( m_windowWidth, m_windowHeight );
+    }
 
     /**
      * Creates a map called "branding" in the global storage, and inserts an
@@ -128,6 +146,9 @@ private:
     bool m_welcomeStyleCalamares;
     bool m_welcomeExpandingLogo;
     WindowExpansion m_windowExpansion;
+
+    WindowDimension m_windowHeight, m_windowWidth;
+
 };
 
 template<typename U> inline QString operator*(U e) { return Branding::instance()->string( e ); }