diff --git a/src/printsupport/dialogs/qprintdialog.h b/src/printsupport/dialogs/qprintdialog.h
index f563836548..975640e6ee 100644
--- a/src/printsupport/dialogs/qprintdialog.h
+++ b/src/printsupport/dialogs/qprintdialog.h
@@ -63,7 +63,7 @@ class Q_PRINTSUPPORT_EXPORT QUnixPrintWidget : public QWidget
     Q_OBJECT
 
 public:
-    QUnixPrintWidget(QPrinter *printer, QWidget *parent = 0);
+    explicit QUnixPrintWidget(QPrinter *printer, QWidget *parent = 0);
     ~QUnixPrintWidget();
     void updatePrinter();
 
diff --git a/src/printsupport/kernel/qprinterinfo.h b/src/printsupport/kernel/qprinterinfo.h
index 64903bee85..d26b70dee0 100644
--- a/src/printsupport/kernel/qprinterinfo.h
+++ b/src/printsupport/kernel/qprinterinfo.h
@@ -59,7 +59,7 @@ class Q_PRINTSUPPORT_EXPORT QPrinterInfo
 public:
     QPrinterInfo();
     QPrinterInfo(const QPrinterInfo &other);
-    QPrinterInfo(const QPrinter &printer);
+    explicit QPrinterInfo(const QPrinter &printer);
     ~QPrinterInfo();
 
     QPrinterInfo &operator=(const QPrinterInfo &other);
@@ -73,7 +73,7 @@ public:
     static QPrinterInfo defaultPrinter();
 
 private:
-    QPrinterInfo(const QString &name);
+    explicit QPrinterInfo(const QString &name);
 
 private:
     friend class QPlatformPrinterSupport;