diff --git a/src/pinentry.hxx b/src/pinentry.hxx
index 9cef88a..4684bc1 100644
--- a/src/pinentry.hxx
+++ b/src/pinentry.hxx
@@ -23,6 +23,7 @@ class PinEntry: public QDialog, public Ui::PinEntry {
     Q_OBJECT;
   public:
     PinEntry(const QSslCertificate& cert, QWidget *parent=0): QDialog(parent) {
+      setModal(true);
       setupUi(this);
       _cert->certificate(cert);
       on__showDetails_toggled(false);