diff --git a/src/widgets/conflictresolvedialog.cpp b/src/widgets/conflictresolvedialog.cpp
--- a/src/widgets/conflictresolvedialog.cpp
+++ b/src/widgets/conflictresolvedialog.cpp
@@ -28,11 +28,14 @@
 #include <QLabel>
 #include <QPushButton>
 #include <QDateTime>
+#include <QWindow>
+#include <QScreen>
 
 #include <kcolorscheme.h>
 #include <KLocalizedString>
 #include <qtextbrowser.h>
 #include <QDialogButtonBox>
+#include <KWindowConfig>
 
 using namespace Akonadi;
 
@@ -217,6 +220,18 @@
     mainLayout->addWidget(mView);
     mainLayout->addWidget(buttonBox);
 
+    // default size is tiny, and there's usually lots of text, so make it much bigger
+    create(); // ensure a window is created
+    const QSize availableSize = windowHandle()->screen()->availableSize();
+    windowHandle()->resize(availableSize.width() * 0.7, availableSize.height() * 0.5);
+    KWindowConfig::restoreWindowSize(windowHandle(), KSharedConfig::openConfig()->group("ConflictResolveDialog"));
+    resize(windowHandle()->size()); // workaround for QTBUG-40584
+}
+
+ConflictResolveDialog::~ConflictResolveDialog()
+{
+    KConfigGroup group(KSharedConfig::openConfig()->group("ConflictResolveDialog"));
+    KWindowConfig::saveWindowSize(windowHandle(), group);
 }
 
 void ConflictResolveDialog::setConflictingItems(const Akonadi::Item &localItem, const Akonadi::Item &otherItem)
diff --git a/src/widgets/conflictresolvedialog_p.h b/src/widgets/conflictresolvedialog_p.h
--- a/src/widgets/conflictresolvedialog_p.h
+++ b/src/widgets/conflictresolvedialog_p.h
@@ -47,6 +47,8 @@
      */
     explicit ConflictResolveDialog(QWidget *parent = nullptr);
 
+    ~ConflictResolveDialog();
+
     /**
      * Sets the items that causes the conflict.
      *