diff --git a/src/filewidgets/kabstractviewadapter.h b/src/filewidgets/kabstractviewadapter.h
--- a/src/filewidgets/kabstractviewadapter.h
+++ b/src/filewidgets/kabstractviewadapter.h
@@ -73,7 +73,7 @@
 public:
     enum Signal { ScrollBarValueChanged, IconSizeChanged };
 
-    KAbstractViewAdapter(QObject *parent) : QObject(parent) {}
+    explicit KAbstractViewAdapter(QObject *parent) : QObject(parent) {}
     virtual ~KAbstractViewAdapter() {}
     virtual QAbstractItemModel *model() const = 0;
     virtual QSize iconSize() const = 0;
diff --git a/src/filewidgets/kdiroperatoriconview_p.h b/src/filewidgets/kdiroperatoriconview_p.h
--- a/src/filewidgets/kdiroperatoriconview_p.h
+++ b/src/filewidgets/kdiroperatoriconview_p.h
@@ -29,7 +29,7 @@
 {
     Q_OBJECT
 public:
-    KDirOperatorIconView(QWidget *parent = nullptr, QStyleOptionViewItem::Position decorationPosition = QStyleOptionViewItem::Position::Top);
+    explicit KDirOperatorIconView(QWidget *parent = nullptr, QStyleOptionViewItem::Position decorationPosition = QStyleOptionViewItem::Position::Top);
     virtual ~KDirOperatorIconView();
     void setDecorationPosition(QStyleOptionViewItem::Position decorationPosition);
 
diff --git a/src/filewidgets/kfileplacesmodel.h b/src/filewidgets/kfileplacesmodel.h
--- a/src/filewidgets/kfileplacesmodel.h
+++ b/src/filewidgets/kfileplacesmodel.h
@@ -73,7 +73,7 @@
     * @since 5.43
     * @todo kf6: merge constructors
     */
-    KFilePlacesModel(const QString &alternativeApplicationName, QObject *parent = nullptr);
+    explicit KFilePlacesModel(const QString &alternativeApplicationName, QObject *parent = nullptr);
     ~KFilePlacesModel() override;
 
     /**
@@ -130,7 +130,7 @@
      * If the index is not valid, a default KBookmark instance is returned.
      */
     KBookmark bookmarkForIndex(const QModelIndex &index) const;
-    
+
     /**
      * @return The KBookmark instance of the place with url @p searchUrl.
      * If the bookmark corresponding to searchUrl is not found, a default KBookmark instance is returned.
diff --git a/src/filewidgets/kfilepreviewgenerator.h b/src/filewidgets/kfilepreviewgenerator.h
--- a/src/filewidgets/kfilepreviewgenerator.h
+++ b/src/filewidgets/kfilepreviewgenerator.h
@@ -61,7 +61,7 @@
      *                the model of the view (or the source model of the proxy model)
      *                is an instance of KDirModel. Otherwise no previews will be generated.
      */
-    KFilePreviewGenerator(QAbstractItemView *parent);
+    explicit KFilePreviewGenerator(QAbstractItemView *parent);
 
     /** @internal */
     KFilePreviewGenerator(KAbstractViewAdapter *parent, QAbstractProxyModel *model);
diff --git a/src/filewidgets/kurlnavigator.h b/src/filewidgets/kurlnavigator.h
--- a/src/filewidgets/kurlnavigator.h
+++ b/src/filewidgets/kurlnavigator.h
@@ -80,7 +80,7 @@
 
 public:
     /** @since 4.5 */
-    KUrlNavigator(QWidget *parent = nullptr);
+    explicit KUrlNavigator(QWidget *parent = nullptr);
 
     /**
      * @param placesModel    Model for the places which are selectable inside a