diff --git a/src/calibre/gui2/__init__.py b/src/calibre/gui2/__init__.py
index d9b69b68af..8d7e5651ed 100644
--- a/src/calibre/gui2/__init__.py
+++ b/src/calibre/gui2/__init__.py
@@ -1149,8 +1149,8 @@ class Application(QApplication):
         if ismacos:
             from calibre_extensions.cocoa import transient_scroller
             transient_scroller = transient_scroller()
-        icon_map[QStyle.StandardPixmap.SP_CustomBase + 1] = I('close-for-light-theme.png')
-        icon_map[QStyle.StandardPixmap.SP_CustomBase + 2] = I('close-for-dark-theme.png')
+        icon_map[(QStyle.StandardPixmap.SP_CustomBase & 0xf0000000) + 1] = I('close-for-light-theme.png')
+        icon_map[(QStyle.StandardPixmap.SP_CustomBase & 0xf0000000) + 2] = I('close-for-dark-theme.png')
         self.pi.load_style(icon_map, transient_scroller)
 
     def _send_file_open_events(self):
diff --git a/src/calibre/gui2/progress_indicator/QProgressIndicator.cpp b/src/calibre/gui2/progress_indicator/QProgressIndicator.cpp
index 0336f3a3f3..ba0e3accc0 100644
--- a/src/calibre/gui2/progress_indicator/QProgressIndicator.cpp
+++ b/src/calibre/gui2/progress_indicator/QProgressIndicator.cpp
@@ -122,13 +122,13 @@ dpiScaled(qreal value) {
 
 class CalibreStyle: public QProxyStyle {
     private:
-        QHash<int, QString> icon_map;
+        const QHash<unsigned long, QString> icon_map;
         QByteArray desktop_environment;
         QDialogButtonBox::ButtonLayout button_layout;
         int transient_scroller;
 
     public:
-        CalibreStyle(QStyle *base, QHash<int, QString> icmap, int transient_scroller) : QProxyStyle(base), icon_map(icmap), transient_scroller(transient_scroller) {
+        CalibreStyle(QStyle *base, const QHash<unsigned long, QString> &icmap, int transient_scroller) : QProxyStyle(base), icon_map(icmap), transient_scroller(transient_scroller) {
             setObjectName(QString("calibre"));
             desktop_environment = detectDesktopEnvironment();
             button_layout = static_cast<QDialogButtonBox::ButtonLayout>(QProxyStyle::styleHint(SH_DialogButtonLayout));
@@ -373,7 +373,7 @@ class CalibreStyle: public QProxyStyle {
 		}
 };
 
-int load_style(QHash<int,QString> icon_map, int transient_scroller) {
+int load_style(const QHash<unsigned long,QString> &icon_map, int transient_scroller) {
     QStyle *base_style = QStyleFactory::create(QString("Fusion"));
     QApplication::setStyle(new CalibreStyle(base_style, icon_map, transient_scroller));
     return 0;
diff --git a/src/calibre/gui2/progress_indicator/QProgressIndicator.h b/src/calibre/gui2/progress_indicator/QProgressIndicator.h
index d76cb32a5b..fdb60b2d05 100644
--- a/src/calibre/gui2/progress_indicator/QProgressIndicator.h
+++ b/src/calibre/gui2/progress_indicator/QProgressIndicator.h
@@ -137,6 +137,6 @@ private:
 	SpinAnimator m_animator;
 };
 
-int load_style(QHash<int,QString> icon_map, int transient_scroller=0);
+int load_style(const QHash<unsigned long,QString> &icon_map, int transient_scroller=0);
 void set_no_activate_on_click(QWidget *widget);
 void draw_snake_spinner(QPainter &painter, QRect rect, int angle, const QColor & light, const QColor & dark);
diff --git a/src/calibre/gui2/progress_indicator/QProgressIndicator.sip b/src/calibre/gui2/progress_indicator/QProgressIndicator.sip
index 7387099234..8230622e85 100644
--- a/src/calibre/gui2/progress_indicator/QProgressIndicator.sip
+++ b/src/calibre/gui2/progress_indicator/QProgressIndicator.sip
@@ -7,7 +7,7 @@
 
 %ModuleHeaderCode
 #include <QPainter>
-int load_style(QHash<int,QString> icon_map, int transient_scroller);
+int load_style(const QHash<unsigned long,QString> &icon_map, int transient_scroller);
 void set_no_activate_on_click(QWidget *widget);
 void draw_snake_spinner(QPainter &painter, QRect rect, int angle, const QColor & light, const QColor & dark);
 %End
@@ -74,6 +74,15 @@ signals:
 
 };
 
-int load_style(QHash<int,QString> icon_map, int transient_scroller);
+int load_style(SIP_PYDICT icon_map_, int transient_scroller);
+%MethodCode
+	QHash<unsigned long,QString> icon_map;
+	PyObject *key, *value;
+	Py_ssize_t pos = 0;
+	while (PyDict_Next(a0, &pos, &key, &value)) {
+		icon_map.insert(PyLong_AsUnsignedLong(key), QString::fromUtf8(PyUnicode_AsUTF8(value)));
+	}
+	load_style(icon_map, a1);
+%End
 void set_no_activate_on_click(QWidget *widget);
 void draw_snake_spinner(QPainter &painter, QRect rect, int angle, const QColor & light, const QColor & dark) /ReleaseGIL/;