diff --git a/samples/geotag.cpp b/samples/geotag.cpp
index 8c8bdae2..b45099fd 100644
--- a/samples/geotag.cpp
+++ b/samples/geotag.cpp
@@ -123,7 +123,7 @@ class Position {
   virtual ~Position() = default;
 
   //  instance methods
-  bool good() const {
+  [[nodiscard]] bool good() const {
     return time_ || lon_ || lat_ || ele_;
   }
   std::string getTimeString() {
@@ -131,22 +131,22 @@ class Position {
       times_ = getExifTime(time_);
     return times_;
   }
-  time_t getTime() const {
+  [[nodiscard]] time_t getTime() const {
     return time_;
   }
-  std::string toString() const;
+  [[nodiscard]] std::string toString() const;
 
   //  getters/setters
-  double lat() const {
+  [[nodiscard]] double lat() const {
     return lat_;
   }
-  double lon() const {
+  [[nodiscard]] double lon() const {
     return lon_;
   }
-  double ele() const {
+  [[nodiscard]] double ele() const {
     return ele_;
   }
-  int delta() const {
+  [[nodiscard]] int delta() const {
     return delta_;
   }
   void delta(int delta) {
diff --git a/src/basicio.cpp b/src/basicio.cpp
index da320f89..97f226c4 100644
--- a/src/basicio.cpp
+++ b/src/basicio.cpp
@@ -619,19 +619,19 @@ class EXIV2API BlockMap {
     size_ = num;
   }
 
-  bool isNone() const {
+  [[nodiscard]] bool isNone() const {
     return type_ == bNone;
   }
 
-  bool isKnown() const {
+  [[nodiscard]] bool isKnown() const {
     return type_ == bKnown;
   }
 
-  byte* getData() const {
+  [[nodiscard]] byte* getData() const {
     return data_;
   }
 
-  size_t getSize() const {
+  [[nodiscard]] size_t getSize() const {
     return size_;
   }
 
diff --git a/src/convert.cpp b/src/convert.cpp
index fa5fa739..61e632a6 100644
--- a/src/convert.cpp
+++ b/src/convert.cpp
@@ -262,7 +262,7 @@ class Converter {
   //! @name Accessors
   //@{
   //! Get the value of the erase flag, see also setErase(bool on).
-  bool erase() const {
+  [[nodiscard]] bool erase() const {
     return erase_;
   }
   //@}
diff --git a/src/exif.cpp b/src/exif.cpp
index 77e194ff..26b562ad 100644
--- a/src/exif.cpp
+++ b/src/exif.cpp
@@ -76,17 +76,17 @@ class Thumbnail {
     @brief Return the thumbnail image in a %DataBuf. The caller owns the
            data buffer and %DataBuf ensures that it will be deleted.
    */
-  virtual Exiv2::DataBuf copy(const Exiv2::ExifData& exifData) const = 0;
+  [[nodiscard]] virtual Exiv2::DataBuf copy(const Exiv2::ExifData& exifData) const = 0;
   /*!
     @brief Return the MIME type of the thumbnail ("image/tiff" or
            "image/jpeg").
    */
-  virtual const char* mimeType() const = 0;
+  [[nodiscard]] virtual const char* mimeType() const = 0;
   /*!
     @brief Return the file extension for the format of the thumbnail
            (".tif", ".jpg").
    */
-  virtual const char* extension() const = 0;
+  [[nodiscard]] virtual const char* extension() const = 0;
   //@}
 
 };  // class Thumbnail
@@ -100,9 +100,9 @@ class TiffThumbnail : public Thumbnail {
 
   //! @name Accessors
   //@{
-  Exiv2::DataBuf copy(const Exiv2::ExifData& exifData) const override;
-  const char* mimeType() const override;
-  const char* extension() const override;
+  [[nodiscard]] Exiv2::DataBuf copy(const Exiv2::ExifData& exifData) const override;
+  [[nodiscard]] const char* mimeType() const override;
+  [[nodiscard]] const char* extension() const override;
   //@}
 
 };  // class TiffThumbnail
@@ -116,9 +116,9 @@ class JpegThumbnail : public Thumbnail {
 
   //! @name Accessors
   //@{
-  Exiv2::DataBuf copy(const Exiv2::ExifData& exifData) const override;
-  const char* mimeType() const override;
-  const char* extension() const override;
+  [[nodiscard]] Exiv2::DataBuf copy(const Exiv2::ExifData& exifData) const override;
+  [[nodiscard]] const char* mimeType() const override;
+  [[nodiscard]] const char* extension() const override;
   //@}
 
 };  // class JpegThumbnail
diff --git a/src/preview.cpp b/src/preview.cpp
index e1faecd4..82d9899c 100644
--- a/src/preview.cpp
+++ b/src/preview.cpp
@@ -58,15 +58,15 @@ class Loader {
   static UniquePtr create(PreviewId id, const Image& image);
 
   //! Check if a preview image with given params exists in the image
-  virtual bool valid() const {
+  [[nodiscard]] virtual bool valid() const {
     return valid_;
   }
 
   //! Get properties of a preview image with given params
-  virtual PreviewProperties getProperties() const;
+  [[nodiscard]] virtual PreviewProperties getProperties() const;
 
   //! Get a buffer that contains the preview image
-  virtual DataBuf getData() const = 0;
+  [[nodiscard]] virtual DataBuf getData() const = 0;
 
   //! Read preview image dimensions when they are not available directly
   virtual bool readDimensions() {
@@ -119,10 +119,10 @@ class LoaderNative : public Loader {
   LoaderNative(PreviewId id, const Image& image, int parIdx);
 
   //! Get properties of a preview image with given params
-  PreviewProperties getProperties() const override;
+  [[nodiscard]] PreviewProperties getProperties() const override;
 
   //! Get a buffer that contains the preview image
-  DataBuf getData() const override;
+  [[nodiscard]] DataBuf getData() const override;
 
   //! Read preview image dimensions
   bool readDimensions() override;
@@ -142,10 +142,10 @@ class LoaderExifJpeg : public Loader {
   LoaderExifJpeg(PreviewId id, const Image& image, int parIdx);
 
   //! Get properties of a preview image with given params
-  PreviewProperties getProperties() const override;
+  [[nodiscard]] PreviewProperties getProperties() const override;
 
   //! Get a buffer that contains the preview image
-  DataBuf getData() const override;
+  [[nodiscard]] DataBuf getData() const override;
 
   //! Read preview image dimensions
   bool readDimensions() override;
@@ -175,10 +175,10 @@ class LoaderExifDataJpeg : public Loader {
   LoaderExifDataJpeg(PreviewId id, const Image& image, int parIdx);
 
   //! Get properties of a preview image with given params
-  PreviewProperties getProperties() const override;
+  [[nodiscard]] PreviewProperties getProperties() const override;
 
   //! Get a buffer that contains the preview image
-  DataBuf getData() const override;
+  [[nodiscard]] DataBuf getData() const override;
 
   //! Read preview image dimensions
   bool readDimensions() override;
@@ -207,10 +207,10 @@ class LoaderTiff : public Loader {
   LoaderTiff(PreviewId id, const Image& image, int parIdx);
 
   //! Get properties of a preview image with given params
-  PreviewProperties getProperties() const override;
+  [[nodiscard]] PreviewProperties getProperties() const override;
 
   //! Get a buffer that contains the preview image
-  DataBuf getData() const override;
+  [[nodiscard]] DataBuf getData() const override;
 
  protected:
   //! Name of the group that contains the preview image
@@ -243,10 +243,10 @@ class LoaderXmpJpeg : public Loader {
   LoaderXmpJpeg(PreviewId id, const Image& image, int parIdx);
 
   //! Get properties of a preview image with given params
-  PreviewProperties getProperties() const override;
+  [[nodiscard]] PreviewProperties getProperties() const override;
 
   //! Get a buffer that contains the preview image
-  DataBuf getData() const override;
+  [[nodiscard]] DataBuf getData() const override;
 
   //! Read preview image dimensions
   bool readDimensions() override;
diff --git a/src/tags.cpp b/src/tags.cpp
index 679ee9fa..50939665 100644
--- a/src/tags.cpp
+++ b/src/tags.cpp
@@ -168,7 +168,7 @@ struct ExifKey::Impl {
   //! @name Accessors
   //@{
   //! Return the name of the tag
-  std::string tagName() const;
+  [[nodiscard]] std::string tagName() const;
   //@}
 
   // DATA