diff --git a/mediafileinfo.h b/mediafileinfo.h
index 58d2715..35b9ee5 100644
--- a/mediafileinfo.h
+++ b/mediafileinfo.h
@@ -27,7 +27,7 @@ class VorbisComment;
 class Diagnostics;
 class AbortableProgressFeedback;
 
-enum class MediaType;
+DECLARE_ENUM_CLASS(MediaType, unsigned int);
 DECLARE_ENUM_CLASS(TagType, unsigned int);
 
 /*!
diff --git a/mediaformat.h b/mediaformat.h
index ee91824..19c444d 100644
--- a/mediaformat.h
+++ b/mediaformat.h
@@ -10,7 +10,7 @@ namespace TagParser {
 /*!
  * \brief The MediaType enum specifies the type of media data (audio, video, text, ...).
  */
-enum class MediaType {
+enum class MediaType : unsigned int {
     Unknown, /**< the type is unknown */
     Audio, /**< audio/sound */
     Video, /**< video */
@@ -25,7 +25,7 @@ extern const char *TAG_PARSER_EXPORT mediaTypeName(MediaType mediaType);
 /*!
  * \brief The GeneralMediaFormat enum specifies the general format of media data (PCM, MPEG-4, PNG, ...).
  */
-enum class GeneralMediaFormat {
+enum class GeneralMediaFormat : unsigned int {
     Unknown, /**< the format is unknown */
     Aac, /**< Advanced Video Coding */
     Ac3, /**< Dolby Digital */
diff --git a/signature.h b/signature.h
index 05391c6..d7f71ea 100644
--- a/signature.h
+++ b/signature.h
@@ -14,7 +14,7 @@ DECLARE_ENUM_CLASS(TagTargetLevel, byte);
  *
  * Raw streams like ADTS or raw FLAC count as container format in this context.
  */
-enum class ContainerFormat {
+enum class ContainerFormat : unsigned int {
     Unknown, /**< unknown container format */
     Ac3Frames, /**< raw AC-3/Dolby Digital frames */
     Adts, /**< Audio Data Transport Stream */