diff --git a/src/calibre/gui2/metadata/diff.py b/src/calibre/gui2/metadata/diff.py
index 057fce6e92..389dbc7cb1 100644
--- a/src/calibre/gui2/metadata/diff.py
+++ b/src/calibre/gui2/metadata/diff.py
@@ -372,7 +372,7 @@ class CoverView(QWidget):
             f.setBold(True)
             p.setFont(f)
             sz = u'\u00a0%d x %d\u00a0'%(self.pixmap.width(), self.pixmap.height())
-            flags = Qt.AlignBottom|Qt.AlignRight|Qt.TextSingleLine
+            flags = int(Qt.AlignBottom|Qt.AlignRight|Qt.TextSingleLine)
             szrect = p.boundingRect(sztgt, flags, sz)
             p.fillRect(szrect.adjusted(0, 0, 0, 4), QColor(0, 0, 0, 200))
             p.setPen(QPen(QColor(255,255,255)))