diff --git a/Cargo.toml b/Cargo.toml
index e05780a..f71b574 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,6 +9,7 @@ readme = "README.md"
 license = "MIT"
 keywords = ["hls", "m3u8"]
 edition = "2018"
+categories = ["parser"]
 
 [badges]
 travis-ci = {repository = "sile/hls_m3u8"}
@@ -18,4 +19,4 @@ codecov = {repository = "sile/hls_m3u8"}
 trackable = "0.2"
 
 [dev-dependencies]
-clap = "2"
\ No newline at end of file
+clap = "2"
diff --git a/src/lib.rs b/src/lib.rs
index 889d757..409ba59 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,3 +1,8 @@
+#![warn(
+    //clippy::pedantic,
+    clippy::nursery,
+    clippy::cargo
+)]
 //! [HLS] m3u8 parser/generator.
 //!
 //! [HLS]: https://tools.ietf.org/html/rfc8216
diff --git a/src/line.rs b/src/line.rs
index 6b1b1f6..974d01d 100644
--- a/src/line.rs
+++ b/src/line.rs
@@ -9,7 +9,7 @@ pub struct Lines<'a> {
     input: &'a str,
 }
 impl<'a> Lines<'a> {
-    pub fn new(input: &'a str) -> Self {
+    pub const fn new(input: &'a str) -> Self {
         Lines { input }
     }
 
diff --git a/src/master_playlist.rs b/src/master_playlist.rs
index 40fc065..48a4453 100644
--- a/src/master_playlist.rs
+++ b/src/master_playlist.rs
@@ -238,17 +238,17 @@ pub struct MasterPlaylist {
 
 impl MasterPlaylist {
     /// Returns the `EXT-X-VERSION` tag contained in the playlist.
-    pub fn version_tag(&self) -> ExtXVersion {
+    pub const fn version_tag(&self) -> ExtXVersion {
         self.version_tag
     }
 
     /// Returns the `EXT-X-INDEPENDENT-SEGMENTS` tag contained in the playlist.
-    pub fn independent_segments_tag(&self) -> Option<ExtXIndependentSegments> {
+    pub const fn independent_segments_tag(&self) -> Option<ExtXIndependentSegments> {
         self.independent_segments_tag
     }
 
     /// Returns the `EXT-X-START` tag contained in the playlist.
-    pub fn start_tag(&self) -> Option<ExtXStart> {
+    pub const fn start_tag(&self) -> Option<ExtXStart> {
         self.start_tag
     }
 
diff --git a/src/media_playlist.rs b/src/media_playlist.rs
index a25d816..2f5b7a4 100644
--- a/src/media_playlist.rs
+++ b/src/media_playlist.rs
@@ -27,6 +27,7 @@ pub struct MediaPlaylistBuilder {
     segments: Vec<MediaSegment>,
     options: MediaPlaylistOptions,
 }
+
 impl MediaPlaylistBuilder {
     /// Makes a new `MediaPlaylistBuilder` instance.
     pub fn new() -> Self {
@@ -180,6 +181,7 @@ impl MediaPlaylistBuilder {
             .unwrap_or(ProtocolVersion::V1)
     }
 }
+
 impl Default for MediaPlaylistBuilder {
     fn default() -> Self {
         Self::new()
@@ -200,49 +202,50 @@ pub struct MediaPlaylist {
     end_list_tag: Option<ExtXEndList>,
     segments: Vec<MediaSegment>,
 }
+
 impl MediaPlaylist {
     /// Returns the `EXT-X-VERSION` tag contained in the playlist.
-    pub fn version_tag(&self) -> ExtXVersion {
+    pub const fn version_tag(&self) -> ExtXVersion {
         self.version_tag
     }
 
     /// Returns the `EXT-X-TARGETDURATION` tag contained in the playlist.
-    pub fn target_duration_tag(&self) -> ExtXTargetDuration {
+    pub const fn target_duration_tag(&self) -> ExtXTargetDuration {
         self.target_duration_tag
     }
 
     /// Returns the `EXT-X-MEDIA-SEQUENCE` tag contained in the playlist.
-    pub fn media_sequence_tag(&self) -> Option<ExtXMediaSequence> {
+    pub const fn media_sequence_tag(&self) -> Option<ExtXMediaSequence> {
         self.media_sequence_tag
     }
 
     /// Returns the `EXT-X-DISCONTINUITY-SEQUENCE` tag contained in the playlist.
-    pub fn discontinuity_sequence_tag(&self) -> Option<ExtXDiscontinuitySequence> {
+    pub const fn discontinuity_sequence_tag(&self) -> Option<ExtXDiscontinuitySequence> {
         self.discontinuity_sequence_tag
     }
 
     /// Returns the `EXT-X-PLAYLIST-TYPE` tag contained in the playlist.
-    pub fn playlist_type_tag(&self) -> Option<ExtXPlaylistType> {
+    pub const fn playlist_type_tag(&self) -> Option<ExtXPlaylistType> {
         self.playlist_type_tag
     }
 
     /// Returns the `EXT-X-I-FRAMES-ONLY` tag contained in the playlist.
-    pub fn i_frames_only_tag(&self) -> Option<ExtXIFramesOnly> {
+    pub const fn i_frames_only_tag(&self) -> Option<ExtXIFramesOnly> {
         self.i_frames_only_tag
     }
 
     /// Returns the `EXT-X-INDEPENDENT-SEGMENTS` tag contained in the playlist.
-    pub fn independent_segments_tag(&self) -> Option<ExtXIndependentSegments> {
+    pub const fn independent_segments_tag(&self) -> Option<ExtXIndependentSegments> {
         self.independent_segments_tag
     }
 
     /// Returns the `EXT-X-START` tag contained in the playlist.
-    pub fn start_tag(&self) -> Option<ExtXStart> {
+    pub const fn start_tag(&self) -> Option<ExtXStart> {
         self.start_tag
     }
 
     /// Returns the `EXT-X-ENDLIST` tag contained in the playlist.
-    pub fn end_list_tag(&self) -> Option<ExtXEndList> {
+    pub const fn end_list_tag(&self) -> Option<ExtXEndList> {
         self.end_list_tag
     }
 
@@ -251,6 +254,7 @@ impl MediaPlaylist {
         &self.segments
     }
 }
+
 impl fmt::Display for MediaPlaylist {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         writeln!(f, "{}", ExtM3u)?;
@@ -285,6 +289,7 @@ impl fmt::Display for MediaPlaylist {
         Ok(())
     }
 }
+
 impl FromStr for MediaPlaylist {
     type Err = Error;
     fn from_str(s: &str) -> Result<Self> {
@@ -297,6 +302,7 @@ impl FromStr for MediaPlaylist {
 pub struct MediaPlaylistOptions {
     allowable_excess_duration: Duration,
 }
+
 impl MediaPlaylistOptions {
     /// Makes a new `MediaPlaylistOptions` with the default settings.
     pub fn new() -> Self {
@@ -450,6 +456,7 @@ impl MediaPlaylistOptions {
         track!(builder.finish())
     }
 }
+
 impl Default for MediaPlaylistOptions {
     fn default() -> Self {
         Self::new()
diff --git a/src/media_segment.rs b/src/media_segment.rs
index 7794819..602b51d 100644
--- a/src/media_segment.rs
+++ b/src/media_segment.rs
@@ -19,6 +19,7 @@ pub struct MediaSegmentBuilder {
     inf_tag: Option<ExtInf>,
     uri: Option<SingleLineString>,
 }
+
 impl MediaSegmentBuilder {
     /// Makes a new `MediaSegmentBuilder` instance.
     pub fn new() -> Self {
@@ -70,6 +71,7 @@ impl MediaSegmentBuilder {
         })
     }
 }
+
 impl Default for MediaSegmentBuilder {
     fn default() -> Self {
         Self::new()
@@ -88,6 +90,7 @@ pub struct MediaSegment {
     inf_tag: ExtInf,
     uri: SingleLineString,
 }
+
 impl fmt::Display for MediaSegment {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         for t in &self.key_tags {
@@ -113,19 +116,20 @@ impl fmt::Display for MediaSegment {
         Ok(())
     }
 }
+
 impl MediaSegment {
     /// Returns the URI of the media segment.
-    pub fn uri(&self) -> &SingleLineString {
+    pub const fn uri(&self) -> &SingleLineString {
         &self.uri
     }
 
     /// Returns the `EXT-X-INF` tag associated with the media segment.
-    pub fn inf_tag(&self) -> &ExtInf {
+    pub const fn inf_tag(&self) -> &ExtInf {
         &self.inf_tag
     }
 
     /// Returns the `EXT-X-BYTERANGE` tag associated with the media segment.
-    pub fn byte_range_tag(&self) -> Option<ExtXByteRange> {
+    pub const fn byte_range_tag(&self) -> Option<ExtXByteRange> {
         self.byte_range_tag
     }
 
@@ -135,7 +139,7 @@ impl MediaSegment {
     }
 
     /// Returns the `EXT-X-DISCONTINUITY` tag associated with the media segment.
-    pub fn discontinuity_tag(&self) -> Option<ExtXDiscontinuity> {
+    pub const fn discontinuity_tag(&self) -> Option<ExtXDiscontinuity> {
         self.discontinuity_tag
     }
 
diff --git a/src/tags/basic/m3u.rs b/src/tags/basic/m3u.rs
index 5d44b90..9595a18 100644
--- a/src/tags/basic/m3u.rs
+++ b/src/tags/basic/m3u.rs
@@ -8,21 +8,25 @@ use std::str::FromStr;
 /// [4.3.1.1. EXTM3U]: https://tools.ietf.org/html/rfc8216#section-4.3.1.1
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct ExtM3u;
+
 impl ExtM3u {
     pub(crate) const PREFIX: &'static str = "#EXTM3U";
 
     /// Returns the protocol compatibility version that this tag requires.
-    pub fn requires_version(self) -> ProtocolVersion {
+    pub const fn requires_version(&self) -> ProtocolVersion {
         ProtocolVersion::V1
     }
 }
+
 impl fmt::Display for ExtM3u {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         Self::PREFIX.fmt(f)
     }
 }
+
 impl FromStr for ExtM3u {
     type Err = Error;
+
     fn from_str(s: &str) -> Result<Self> {
         track_assert_eq!(s, Self::PREFIX, ErrorKind::InvalidInput);
         Ok(ExtM3u)
diff --git a/src/tags/basic/version.rs b/src/tags/basic/version.rs
index f0ab35f..c321e21 100644
--- a/src/tags/basic/version.rs
+++ b/src/tags/basic/version.rs
@@ -15,17 +15,17 @@ impl ExtXVersion {
     pub(crate) const PREFIX: &'static str = "#EXT-X-VERSION:";
 
     /// Makes a new `ExtXVersion` tag.
-    pub fn new(version: ProtocolVersion) -> Self {
+    pub const fn new(version: ProtocolVersion) -> Self {
         ExtXVersion { version }
     }
 
     /// Returns the protocol compatibility version of the playlist containing this tag.
-    pub fn version(self) -> ProtocolVersion {
+    pub const fn version(&self) -> ProtocolVersion {
         self.version
     }
 
     /// Returns the protocol compatibility version that this tag requires.
-    pub fn requires_version(self) -> ProtocolVersion {
+    pub const fn requires_version(&self) -> ProtocolVersion {
         ProtocolVersion::V1
     }
 }
diff --git a/src/tags/master_playlist/i_frame_stream_inf.rs b/src/tags/master_playlist/i_frame_stream_inf.rs
index e287fcb..f10082f 100644
--- a/src/tags/master_playlist/i_frame_stream_inf.rs
+++ b/src/tags/master_playlist/i_frame_stream_inf.rs
@@ -37,17 +37,17 @@ impl ExtXIFrameStreamInf {
     }
 
     /// Returns the URI that identifies the associated media playlist.
-    pub fn uri(&self) -> &String {
+    pub const fn uri(&self) -> &String {
         &self.uri
     }
 
     /// Returns the peak segment bit rate of the variant stream.
-    pub fn bandwidth(&self) -> u64 {
+    pub const fn bandwidth(&self) -> u64 {
         self.bandwidth
     }
 
     /// Returns the average segment bit rate of the variant stream.
-    pub fn average_bandwidth(&self) -> Option<u64> {
+    pub const fn average_bandwidth(&self) -> Option<u64> {
         self.average_bandwidth
     }
 
@@ -57,12 +57,12 @@ impl ExtXIFrameStreamInf {
     }
 
     /// Returns the optimal pixel resolution at which to display all the video in the variant stream.
-    pub fn resolution(&self) -> Option<DecimalResolution> {
+    pub const fn resolution(&self) -> Option<DecimalResolution> {
         self.resolution
     }
 
     /// Returns the HDCP level of the variant stream.
-    pub fn hdcp_level(&self) -> Option<HdcpLevel> {
+    pub const fn hdcp_level(&self) -> Option<HdcpLevel> {
         self.hdcp_level
     }
 
@@ -72,7 +72,7 @@ impl ExtXIFrameStreamInf {
     }
 
     /// Returns the protocol compatibility version that this tag requires.
-    pub fn requires_version(&self) -> ProtocolVersion {
+    pub const fn requires_version(&self) -> ProtocolVersion {
         ProtocolVersion::V1
     }
 }
@@ -104,6 +104,7 @@ impl fmt::Display for ExtXIFrameStreamInf {
 
 impl FromStr for ExtXIFrameStreamInf {
     type Err = Error;
+
     fn from_str(s: &str) -> Result<Self> {
         track_assert!(s.starts_with(Self::PREFIX), ErrorKind::InvalidInput);
 
diff --git a/src/tags/master_playlist/media.rs b/src/tags/master_playlist/media.rs
index 24d2c22..7c17b3b 100644
--- a/src/tags/master_playlist/media.rs
+++ b/src/tags/master_playlist/media.rs
@@ -24,7 +24,7 @@ pub struct ExtXMediaBuilder {
 
 impl ExtXMediaBuilder {
     /// Makes a `ExtXMediaBuilder` instance.
-    pub fn new() -> Self {
+    pub const fn new() -> Self {
         ExtXMediaBuilder {
             media_type: None,
             uri: None,
@@ -194,17 +194,17 @@ impl ExtXMedia {
     }
 
     /// Returns the type of the media associated with this tag.
-    pub fn media_type(&self) -> MediaType {
+    pub const fn media_type(&self) -> MediaType {
         self.media_type
     }
 
     /// Returns the identifier that specifies the group to which the rendition belongs.
-    pub fn group_id(&self) -> &String {
+    pub const fn group_id(&self) -> &String {
         &self.group_id
     }
 
     /// Returns a human-readable description of the rendition.
-    pub fn name(&self) -> &String {
+    pub const fn name(&self) -> &String {
         &self.name
     }
 
@@ -224,23 +224,23 @@ impl ExtXMedia {
     }
 
     /// Returns whether this is the default rendition.
-    pub fn default(&self) -> bool {
+    pub const fn default(&self) -> bool {
         self.default
     }
 
     /// Returns whether the client may choose to
     /// play this rendition in the absence of explicit user preference.
-    pub fn autoselect(&self) -> bool {
+    pub const fn autoselect(&self) -> bool {
         self.autoselect
     }
 
     /// Returns whether the rendition contains content that is considered essential to play.
-    pub fn forced(&self) -> bool {
+    pub const fn forced(&self) -> bool {
         self.forced
     }
 
     /// Returns the identifier that specifies a rendition within the segments in the media playlist.
-    pub fn instream_id(&self) -> Option<InStreamId> {
+    pub const fn instream_id(&self) -> Option<InStreamId> {
         self.instream_id
     }
 
@@ -308,6 +308,7 @@ impl fmt::Display for ExtXMedia {
 
 impl FromStr for ExtXMedia {
     type Err = Error;
+
     fn from_str(s: &str) -> Result<Self> {
         track_assert!(s.starts_with(Self::PREFIX), ErrorKind::InvalidInput);
 
diff --git a/src/tags/master_playlist/session_data.rs b/src/tags/master_playlist/session_data.rs
index 75da90c..32b1633 100644
--- a/src/tags/master_playlist/session_data.rs
+++ b/src/tags/master_playlist/session_data.rs
@@ -37,12 +37,12 @@ impl ExtXSessionData {
     }
 
     /// Returns the identifier of the data.
-    pub fn data_id(&self) -> &String {
+    pub const fn data_id(&self) -> &String {
         &self.data_id
     }
 
     /// Returns the session data.
-    pub fn data(&self) -> &SessionData {
+    pub const fn data(&self) -> &SessionData {
         &self.data
     }
 
@@ -52,7 +52,7 @@ impl ExtXSessionData {
     }
 
     /// Returns the protocol compatibility version that this tag requires.
-    pub fn requires_version(&self) -> ProtocolVersion {
+    pub const fn requires_version(&self) -> ProtocolVersion {
         ProtocolVersion::V1
     }
 }
@@ -74,6 +74,7 @@ impl fmt::Display for ExtXSessionData {
 
 impl FromStr for ExtXSessionData {
     type Err = Error;
+
     fn from_str(s: &str) -> Result<Self> {
         track_assert!(s.starts_with(Self::PREFIX), ErrorKind::InvalidInput);
 
diff --git a/src/tags/master_playlist/session_key.rs b/src/tags/master_playlist/session_key.rs
index aafae51..26cea97 100644
--- a/src/tags/master_playlist/session_key.rs
+++ b/src/tags/master_playlist/session_key.rs
@@ -15,12 +15,12 @@ impl ExtXSessionKey {
     pub(crate) const PREFIX: &'static str = "#EXT-X-SESSION-KEY:";
 
     /// Makes a new `ExtXSessionKey` tag.
-    pub fn new(key: DecryptionKey) -> Self {
+    pub const fn new(key: DecryptionKey) -> Self {
         ExtXSessionKey { key }
     }
 
     /// Returns a decryption key for the playlist.
-    pub fn key(&self) -> &DecryptionKey {
+    pub const fn key(&self) -> &DecryptionKey {
         &self.key
     }
 
diff --git a/src/tags/master_playlist/stream_inf.rs b/src/tags/master_playlist/stream_inf.rs
index 28e5bcd..81c8c28 100644
--- a/src/tags/master_playlist/stream_inf.rs
+++ b/src/tags/master_playlist/stream_inf.rs
@@ -30,7 +30,7 @@ impl ExtXStreamInf {
     pub(crate) const PREFIX: &'static str = "#EXT-X-STREAM-INF:";
 
     /// Makes a new `ExtXStreamInf` tag.
-    pub fn new(uri: SingleLineString, bandwidth: u64) -> Self {
+    pub const fn new(uri: SingleLineString, bandwidth: u64) -> Self {
         ExtXStreamInf {
             uri,
             bandwidth,
@@ -47,17 +47,17 @@ impl ExtXStreamInf {
     }
 
     /// Returns the URI that identifies the associated media playlist.
-    pub fn uri(&self) -> &SingleLineString {
+    pub const fn uri(&self) -> &SingleLineString {
         &self.uri
     }
 
     /// Returns the peak segment bit rate of the variant stream.
-    pub fn bandwidth(&self) -> u64 {
+    pub const fn bandwidth(&self) -> u64 {
         self.bandwidth
     }
 
     /// Returns the average segment bit rate of the variant stream.
-    pub fn average_bandwidth(&self) -> Option<u64> {
+    pub const fn average_bandwidth(&self) -> Option<u64> {
         self.average_bandwidth
     }
 
@@ -67,17 +67,17 @@ impl ExtXStreamInf {
     }
 
     /// Returns the optimal pixel resolution at which to display all the video in the variant stream.
-    pub fn resolution(&self) -> Option<DecimalResolution> {
+    pub const fn resolution(&self) -> Option<DecimalResolution> {
         self.resolution
     }
 
     /// Returns the maximum frame rate for all the video in the variant stream.
-    pub fn frame_rate(&self) -> Option<DecimalFloatingPoint> {
+    pub const fn frame_rate(&self) -> Option<DecimalFloatingPoint> {
         self.frame_rate
     }
 
     /// Returns the HDCP level of the variant stream.
-    pub fn hdcp_level(&self) -> Option<HdcpLevel> {
+    pub const fn hdcp_level(&self) -> Option<HdcpLevel> {
         self.hdcp_level
     }
 
@@ -102,7 +102,7 @@ impl ExtXStreamInf {
     }
 
     /// Returns the protocol compatibility version that this tag requires.
-    pub fn requires_version(&self) -> ProtocolVersion {
+    pub const fn requires_version(&self) -> ProtocolVersion {
         ProtocolVersion::V1
     }
 }
@@ -145,6 +145,7 @@ impl fmt::Display for ExtXStreamInf {
 
 impl FromStr for ExtXStreamInf {
     type Err = Error;
+
     fn from_str(s: &str) -> Result<Self> {
         let mut lines = s.splitn(2, '\n');
         let first_line = lines.next().expect("Never fails").trim_end_matches('\r');
diff --git a/src/tags/media_playlist/discontinuity_sequence.rs b/src/tags/media_playlist/discontinuity_sequence.rs
index 9aa6539..07b245b 100644
--- a/src/tags/media_playlist/discontinuity_sequence.rs
+++ b/src/tags/media_playlist/discontinuity_sequence.rs
@@ -16,18 +16,18 @@ impl ExtXDiscontinuitySequence {
     pub(crate) const PREFIX: &'static str = "#EXT-X-DISCONTINUITY-SEQUENCE:";
 
     /// Makes a new `ExtXDiscontinuitySequence` tag.
-    pub fn new(seq_num: u64) -> Self {
+    pub const fn new(seq_num: u64) -> Self {
         ExtXDiscontinuitySequence { seq_num }
     }
 
     /// Returns the discontinuity sequence number of
     /// the first media segment that appears in the associated playlist.
-    pub fn seq_num(self) -> u64 {
+    pub const fn seq_num(self) -> u64 {
         self.seq_num
     }
 
     /// Returns the protocol compatibility version that this tag requires.
-    pub fn requires_version(self) -> ProtocolVersion {
+    pub const fn requires_version(self) -> ProtocolVersion {
         ProtocolVersion::V1
     }
 }
@@ -40,6 +40,7 @@ impl fmt::Display for ExtXDiscontinuitySequence {
 
 impl FromStr for ExtXDiscontinuitySequence {
     type Err = Error;
+
     fn from_str(s: &str) -> Result<Self> {
         track_assert!(s.starts_with(Self::PREFIX), ErrorKind::InvalidInput);
         let seq_num = may_invalid!(s.split_at(Self::PREFIX.len()).1.parse())?;
diff --git a/src/tags/media_playlist/end_list.rs b/src/tags/media_playlist/end_list.rs
index f8e333f..ddeb5c0 100644
--- a/src/tags/media_playlist/end_list.rs
+++ b/src/tags/media_playlist/end_list.rs
@@ -12,17 +12,20 @@ impl ExtXEndList {
     pub(crate) const PREFIX: &'static str = "#EXT-X-ENDLIST";
 
     /// Returns the protocol compatibility version that this tag requires.
-    pub fn requires_version(self) -> ProtocolVersion {
+    pub const fn requires_version(self) -> ProtocolVersion {
         ProtocolVersion::V1
     }
 }
+
 impl fmt::Display for ExtXEndList {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         Self::PREFIX.fmt(f)
     }
 }
+
 impl FromStr for ExtXEndList {
     type Err = Error;
+
     fn from_str(s: &str) -> Result<Self> {
         track_assert_eq!(s, Self::PREFIX, ErrorKind::InvalidInput);
         Ok(ExtXEndList)
diff --git a/src/tags/media_playlist/i_frames_only.rs b/src/tags/media_playlist/i_frames_only.rs
index 4bea636..90db7f4 100644
--- a/src/tags/media_playlist/i_frames_only.rs
+++ b/src/tags/media_playlist/i_frames_only.rs
@@ -13,7 +13,7 @@ impl ExtXIFramesOnly {
     pub(crate) const PREFIX: &'static str = "#EXT-X-I-FRAMES-ONLY";
 
     /// Returns the protocol compatibility version that this tag requires.
-    pub fn requires_version(self) -> ProtocolVersion {
+    pub const fn requires_version(self) -> ProtocolVersion {
         ProtocolVersion::V4
     }
 }
@@ -26,6 +26,7 @@ impl fmt::Display for ExtXIFramesOnly {
 
 impl FromStr for ExtXIFramesOnly {
     type Err = Error;
+
     fn from_str(s: &str) -> Result<Self> {
         track_assert_eq!(s, Self::PREFIX, ErrorKind::InvalidInput);
         Ok(ExtXIFramesOnly)
diff --git a/src/tags/media_playlist/media_sequence.rs b/src/tags/media_playlist/media_sequence.rs
index 99be333..47f75bf 100644
--- a/src/tags/media_playlist/media_sequence.rs
+++ b/src/tags/media_playlist/media_sequence.rs
@@ -16,17 +16,17 @@ impl ExtXMediaSequence {
     pub(crate) const PREFIX: &'static str = "#EXT-X-MEDIA-SEQUENCE:";
 
     /// Makes a new `ExtXMediaSequence` tag.
-    pub fn new(seq_num: u64) -> Self {
+    pub const fn new(seq_num: u64) -> Self {
         ExtXMediaSequence { seq_num }
     }
 
     /// Returns the sequence number of the first media segment that appears in the associated playlist.
-    pub fn seq_num(self) -> u64 {
+    pub const fn seq_num(self) -> u64 {
         self.seq_num
     }
 
     /// Returns the protocol compatibility version that this tag requires.
-    pub fn requires_version(self) -> ProtocolVersion {
+    pub const fn requires_version(self) -> ProtocolVersion {
         ProtocolVersion::V1
     }
 }
@@ -39,6 +39,7 @@ impl fmt::Display for ExtXMediaSequence {
 
 impl FromStr for ExtXMediaSequence {
     type Err = Error;
+
     fn from_str(s: &str) -> Result<Self> {
         track_assert!(s.starts_with(Self::PREFIX), ErrorKind::InvalidInput);
         let seq_num = may_invalid!(s.split_at(Self::PREFIX.len()).1.parse())?;
diff --git a/src/tags/media_playlist/playlist_type.rs b/src/tags/media_playlist/playlist_type.rs
index e2a5f99..16d9672 100644
--- a/src/tags/media_playlist/playlist_type.rs
+++ b/src/tags/media_playlist/playlist_type.rs
@@ -16,17 +16,17 @@ impl ExtXPlaylistType {
     pub(crate) const PREFIX: &'static str = "#EXT-X-PLAYLIST-TYPE:";
 
     /// Makes a new `ExtXPlaylistType` tag.
-    pub fn new(playlist_type: PlaylistType) -> Self {
+    pub const fn new(playlist_type: PlaylistType) -> Self {
         ExtXPlaylistType { playlist_type }
     }
 
     /// Returns the type of the associated media playlist.
-    pub fn playlist_type(self) -> PlaylistType {
+    pub const fn playlist_type(self) -> PlaylistType {
         self.playlist_type
     }
 
     /// Returns the protocol compatibility version that this tag requires.
-    pub fn requires_version(self) -> ProtocolVersion {
+    pub const fn requires_version(self) -> ProtocolVersion {
         ProtocolVersion::V1
     }
 }
@@ -39,6 +39,7 @@ impl fmt::Display for ExtXPlaylistType {
 
 impl FromStr for ExtXPlaylistType {
     type Err = Error;
+
     fn from_str(s: &str) -> Result<Self> {
         track_assert!(s.starts_with(Self::PREFIX), ErrorKind::InvalidInput);
         let playlist_type = may_invalid!(s.split_at(Self::PREFIX.len()).1.parse())?;
diff --git a/src/tags/media_playlist/target_duration.rs b/src/tags/media_playlist/target_duration.rs
index a2af667..2f759b9 100644
--- a/src/tags/media_playlist/target_duration.rs
+++ b/src/tags/media_playlist/target_duration.rs
@@ -19,18 +19,18 @@ impl ExtXTargetDuration {
     /// Makes a new `ExtXTargetduration` tag.
     ///
     /// Note that the nanoseconds part of the `duration` will be discarded.
-    pub fn new(duration: Duration) -> Self {
+    pub const fn new(duration: Duration) -> Self {
         let duration = Duration::from_secs(duration.as_secs());
         ExtXTargetDuration { duration }
     }
 
     /// Returns the maximum media segment duration in the associated playlist.
-    pub fn duration(&self) -> Duration {
+    pub const fn duration(&self) -> Duration {
         self.duration
     }
 
     /// Returns the protocol compatibility version that this tag requires.
-    pub fn requires_version(&self) -> ProtocolVersion {
+    pub const fn requires_version(&self) -> ProtocolVersion {
         ProtocolVersion::V1
     }
 }
diff --git a/src/tags/media_segment/byte_range.rs b/src/tags/media_segment/byte_range.rs
index 52397ba..bbc5ab1 100644
--- a/src/tags/media_segment/byte_range.rs
+++ b/src/tags/media_segment/byte_range.rs
@@ -16,17 +16,17 @@ impl ExtXByteRange {
     pub(crate) const PREFIX: &'static str = "#EXT-X-BYTERANGE:";
 
     /// Makes a new `ExtXByteRange` tag.
-    pub fn new(range: ByteRange) -> Self {
+    pub const fn new(range: ByteRange) -> Self {
         ExtXByteRange { range }
     }
 
     /// Returns the range of the associated media segment.
-    pub fn range(&self) -> ByteRange {
+    pub const fn range(&self) -> ByteRange {
         self.range
     }
 
     /// Returns the protocol compatibility version that this tag requires.
-    pub fn requires_version(&self) -> ProtocolVersion {
+    pub const fn requires_version(&self) -> ProtocolVersion {
         ProtocolVersion::V4
     }
 }
@@ -39,6 +39,7 @@ impl fmt::Display for ExtXByteRange {
 
 impl FromStr for ExtXByteRange {
     type Err = Error;
+
     fn from_str(s: &str) -> Result<Self> {
         track_assert!(s.starts_with(Self::PREFIX), ErrorKind::InvalidInput);
         let range = may_invalid!(s.split_at(Self::PREFIX.len()).1.parse())?;
diff --git a/src/tags/media_segment/date_range.rs b/src/tags/media_segment/date_range.rs
index 788bd8c..dae13ce 100644
--- a/src/tags/media_segment/date_range.rs
+++ b/src/tags/media_segment/date_range.rs
@@ -32,7 +32,7 @@ impl ExtXDateRange {
     pub(crate) const PREFIX: &'static str = "#EXT-X-DATERANGE:";
 
     /// Returns the protocol compatibility version that this tag requires.
-    pub fn requires_version(&self) -> ProtocolVersion {
+    pub const fn requires_version(&self) -> ProtocolVersion {
         ProtocolVersion::V1
     }
 }
diff --git a/src/tags/media_segment/discontinuity.rs b/src/tags/media_segment/discontinuity.rs
index 8e23325..d0f3563 100644
--- a/src/tags/media_segment/discontinuity.rs
+++ b/src/tags/media_segment/discontinuity.rs
@@ -12,15 +12,17 @@ impl ExtXDiscontinuity {
     pub(crate) const PREFIX: &'static str = "#EXT-X-DISCONTINUITY";
 
     /// Returns the protocol compatibility version that this tag requires.
-    pub fn requires_version(self) -> ProtocolVersion {
+    pub const fn requires_version(self) -> ProtocolVersion {
         ProtocolVersion::V1
     }
 }
+
 impl fmt::Display for ExtXDiscontinuity {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         Self::PREFIX.fmt(f)
     }
 }
+
 impl FromStr for ExtXDiscontinuity {
     type Err = Error;
     fn from_str(s: &str) -> Result<Self> {
diff --git a/src/tags/media_segment/inf.rs b/src/tags/media_segment/inf.rs
index 3543f69..ac215af 100644
--- a/src/tags/media_segment/inf.rs
+++ b/src/tags/media_segment/inf.rs
@@ -18,7 +18,7 @@ impl ExtInf {
     pub(crate) const PREFIX: &'static str = "#EXTINF:";
 
     /// Makes a new `ExtInf` tag.
-    pub fn new(duration: Duration) -> Self {
+    pub const fn new(duration: Duration) -> Self {
         ExtInf {
             duration,
             title: None,
@@ -26,7 +26,7 @@ impl ExtInf {
     }
 
     /// Makes a new `ExtInf` tag with the given title.
-    pub fn with_title(duration: Duration, title: SingleLineString) -> Self {
+    pub const fn with_title(duration: Duration, title: SingleLineString) -> Self {
         ExtInf {
             duration,
             title: Some(title),
@@ -34,7 +34,7 @@ impl ExtInf {
     }
 
     /// Returns the duration of the associated media segment.
-    pub fn duration(&self) -> Duration {
+    pub const fn duration(&self) -> Duration {
         self.duration
     }
 
diff --git a/src/tags/media_segment/key.rs b/src/tags/media_segment/key.rs
index 9f2811f..e9dda27 100644
--- a/src/tags/media_segment/key.rs
+++ b/src/tags/media_segment/key.rs
@@ -16,14 +16,14 @@ impl ExtXKey {
     pub(crate) const PREFIX: &'static str = "#EXT-X-KEY:";
 
     /// Makes a new `ExtXKey` tag.
-    pub fn new(key: DecryptionKey) -> Self {
+    pub const fn new(key: DecryptionKey) -> Self {
         ExtXKey { key: Some(key) }
     }
 
     /// Makes a new `ExtXKey` tag without a decryption key.
     ///
     /// This tag has the `METHDO=NONE` attribute.
-    pub fn new_without_key() -> Self {
+    pub const fn new_without_key() -> Self {
         ExtXKey { key: None }
     }
 
@@ -54,6 +54,7 @@ impl fmt::Display for ExtXKey {
 
 impl FromStr for ExtXKey {
     type Err = Error;
+
     fn from_str(s: &str) -> Result<Self> {
         track_assert!(s.starts_with(Self::PREFIX), ErrorKind::InvalidInput);
         let suffix = s.split_at(Self::PREFIX.len()).1;
diff --git a/src/tags/media_segment/map.rs b/src/tags/media_segment/map.rs
index 96c45f8..c5c9933 100644
--- a/src/tags/media_segment/map.rs
+++ b/src/tags/media_segment/map.rs
@@ -34,17 +34,17 @@ impl ExtXMap {
     }
 
     /// Returns the URI that identifies a resource that contains the media initialization section.
-    pub fn uri(&self) -> &String {
+    pub const fn uri(&self) -> &String {
         &self.uri
     }
 
     /// Returns the range of the media initialization section.
-    pub fn range(&self) -> Option<ByteRange> {
+    pub const fn range(&self) -> Option<ByteRange> {
         self.range
     }
 
     /// Returns the protocol compatibility version that this tag requires.
-    pub fn requires_version(&self) -> ProtocolVersion {
+    pub const fn requires_version(&self) -> ProtocolVersion {
         ProtocolVersion::V6
     }
 }
@@ -62,6 +62,7 @@ impl fmt::Display for ExtXMap {
 
 impl FromStr for ExtXMap {
     type Err = Error;
+
     fn from_str(s: &str) -> Result<Self> {
         track_assert!(s.starts_with(Self::PREFIX), ErrorKind::InvalidInput);
 
diff --git a/src/tags/media_segment/program_date_time.rs b/src/tags/media_segment/program_date_time.rs
index b694c93..625fdeb 100644
--- a/src/tags/media_segment/program_date_time.rs
+++ b/src/tags/media_segment/program_date_time.rs
@@ -15,17 +15,17 @@ impl ExtXProgramDateTime {
     pub(crate) const PREFIX: &'static str = "#EXT-X-PROGRAM-DATE-TIME:";
 
     /// Makes a new `ExtXProgramDateTime` tag.
-    pub fn new(date_time: SingleLineString) -> Self {
+    pub const fn new(date_time: SingleLineString) -> Self {
         ExtXProgramDateTime { date_time }
     }
 
     /// Returns the date-time of the first sample of the associated media segment.
-    pub fn date_time(&self) -> &SingleLineString {
+    pub const fn date_time(&self) -> &SingleLineString {
         &self.date_time
     }
 
     /// Returns the protocol compatibility version that this tag requires.
-    pub fn requires_version(&self) -> ProtocolVersion {
+    pub const fn requires_version(&self) -> ProtocolVersion {
         ProtocolVersion::V1
     }
 }
@@ -38,6 +38,7 @@ impl fmt::Display for ExtXProgramDateTime {
 
 impl FromStr for ExtXProgramDateTime {
     type Err = Error;
+
     fn from_str(s: &str) -> Result<Self> {
         track_assert!(s.starts_with(Self::PREFIX), ErrorKind::InvalidInput);
         let suffix = s.split_at(Self::PREFIX.len()).1;
diff --git a/src/tags/shared/independent_segments.rs b/src/tags/shared/independent_segments.rs
index d4916f9..2aa3e82 100644
--- a/src/tags/shared/independent_segments.rs
+++ b/src/tags/shared/independent_segments.rs
@@ -12,7 +12,7 @@ impl ExtXIndependentSegments {
     pub(crate) const PREFIX: &'static str = "#EXT-X-INDEPENDENT-SEGMENTS";
 
     /// Returns the protocol compatibility version that this tag requires.
-    pub fn requires_version(self) -> ProtocolVersion {
+    pub const fn requires_version(&self) -> ProtocolVersion {
         ProtocolVersion::V1
     }
 }
@@ -25,6 +25,7 @@ impl fmt::Display for ExtXIndependentSegments {
 
 impl FromStr for ExtXIndependentSegments {
     type Err = Error;
+
     fn from_str(s: &str) -> Result<Self> {
         track_assert_eq!(s, Self::PREFIX, ErrorKind::InvalidInput);
         Ok(ExtXIndependentSegments)
diff --git a/src/tags/shared/start.rs b/src/tags/shared/start.rs
index 5c301c1..560b144 100644
--- a/src/tags/shared/start.rs
+++ b/src/tags/shared/start.rs
@@ -18,7 +18,7 @@ impl ExtXStart {
     pub(crate) const PREFIX: &'static str = "#EXT-X-START:";
 
     /// Makes a new `ExtXStart` tag.
-    pub fn new(time_offset: SignedDecimalFloatingPoint) -> Self {
+    pub const fn new(time_offset: SignedDecimalFloatingPoint) -> Self {
         ExtXStart {
             time_offset,
             precise: false,
@@ -26,7 +26,7 @@ impl ExtXStart {
     }
 
     /// Makes a new `ExtXStart` tag with the given `precise` flag.
-    pub fn with_precise(time_offset: SignedDecimalFloatingPoint, precise: bool) -> Self {
+    pub const fn with_precise(time_offset: SignedDecimalFloatingPoint, precise: bool) -> Self {
         ExtXStart {
             time_offset,
             precise,
@@ -34,18 +34,18 @@ impl ExtXStart {
     }
 
     /// Returns the time offset of the media segments in the playlist.
-    pub fn time_offset(&self) -> SignedDecimalFloatingPoint {
+    pub const fn time_offset(&self) -> SignedDecimalFloatingPoint {
         self.time_offset
     }
 
     /// Returns whether clients should not render media stream whose presentation times are
     /// prior to the specified time offset.
-    pub fn precise(&self) -> bool {
+    pub const fn precise(&self) -> bool {
         self.precise
     }
 
     /// Returns the protocol compatibility version that this tag requires.
-    pub fn requires_version(&self) -> ProtocolVersion {
+    pub const fn requires_version(&self) -> ProtocolVersion {
         ProtocolVersion::V1
     }
 }
@@ -63,6 +63,7 @@ impl fmt::Display for ExtXStart {
 
 impl FromStr for ExtXStart {
     type Err = Error;
+
     fn from_str(s: &str) -> Result<Self> {
         track_assert!(s.starts_with(Self::PREFIX), ErrorKind::InvalidInput);
 
diff --git a/src/types/decimal_floating_point.rs b/src/types/decimal_floating_point.rs
index 5cd33cc..aa555e9 100644
--- a/src/types/decimal_floating_point.rs
+++ b/src/types/decimal_floating_point.rs
@@ -26,7 +26,7 @@ impl DecimalFloatingPoint {
     }
 
     /// Converts `DecimalFloatingPoint` to `f64`.
-    pub fn as_f64(self) -> f64 {
+    pub const fn as_f64(self) -> f64 {
         self.0
     }
 
diff --git a/src/types/signed_decimal_floating_point.rs b/src/types/signed_decimal_floating_point.rs
index 3c50998..999d0a2 100644
--- a/src/types/signed_decimal_floating_point.rs
+++ b/src/types/signed_decimal_floating_point.rs
@@ -24,7 +24,7 @@ impl SignedDecimalFloatingPoint {
     }
 
     /// Converts `DecimalFloatingPoint` to `f64`.
-    pub fn as_f64(self) -> f64 {
+    pub const fn as_f64(self) -> f64 {
         self.0
     }
 }