diff --git a/src/externalextractor.h b/src/externalextractor.h
--- a/src/externalextractor.h
+++ b/src/externalextractor.h
@@ -34,7 +34,7 @@
 
 public:
     explicit ExternalExtractor(QObject* parent = nullptr);
-    ExternalExtractor(const QString& pluginPath);
+    explicit ExternalExtractor(const QString& pluginPath);
     virtual ~ExternalExtractor();
 
     QStringList mimetypes() const override;
diff --git a/src/writers/taglibwriter.h b/src/writers/taglibwriter.h
--- a/src/writers/taglibwriter.h
+++ b/src/writers/taglibwriter.h
@@ -33,7 +33,7 @@
     Q_INTERFACES(KFileMetaData::WriterPlugin)
 
 public:
-    TagLibWriter(QObject* parent = nullptr);
+    explicit TagLibWriter(QObject* parent = nullptr);
 
     void write(const WriteData& data) override;
     QStringList writeMimetypes() const override;