diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
index db9efdc..e19421d 100644
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -11,7 +11,7 @@ env:
   CARGO_TERM_COLOR: always
   RUST_BACKTRACE: 1
   RUSTFLAGS: -D warnings
-  RUSTDOCFLAGS: -D warnings --cfg docsrs
+  RUSTDOCFLAGS: -D warnings
 
 jobs:
   build:
@@ -44,6 +44,8 @@ jobs:
       run: cd $(find target/package/ -maxdepth 1 -mindepth 1 -type d) && cargo test --no-default-features
     - name: Build docs
       if: matrix.rust == 'nightly'
+      env:
+        RUSTDOCFLAGS: -D warnings --cfg docsrs
       run: cargo doc --all-features --verbose
     - name: Check formatting
       if: matrix.rust == 'stable'
diff --git a/Cargo.toml b/Cargo.toml
index 3545601..bf1a0ae 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -40,4 +40,8 @@ features = ["alloc"]
 
 [features]
 default = ["std"]
+ks_x_1026-1 = []
 std = []
+
+[package.metadata.docs.rs]
+rustc-args = ["--cfg", "feature=\"ks_x_1026-1\""]
diff --git a/README.md b/README.md
index 7d10e4d..5e169ed 100644
--- a/README.md
+++ b/README.md
@@ -26,8 +26,8 @@ fn main() {
 
 ## crates.io
 
-You can use this package in your project by adding the following
-to your `Cargo.toml`:
+You can use this package in your project by adding the following to your
+`Cargo.toml`:
 
 ```toml
 [dependencies]
@@ -36,4 +36,15 @@ unicode-normalization = "0.1.23"
 
 ## `no_std` + `alloc` support
 
-This crate is completely `no_std` + `alloc` compatible. This can be enabled by disabling the `std` feature, i.e. specifying `default-features = false` for this crate on your `Cargo.toml`.
+This crate is completely `no_std` + `alloc` compatible. This can be enabled by
+disabling the `std` feature, i.e. specifying `default-features = false` for this
+crate on your `Cargo.toml`.
+
+## KS X 1026-1
+
+Korean Standard KS X 1026-1 ([Korean](https://standard.go.kr/KSCI/standardIntro/getStandardSearchView.do?ksNo=KSX1026-1),
+[English](http://std.dkuug.dk/jtc1/sc2/wg2/docs/n3422.pdf)) is an ROK government
+standard that corrects some defects and makes some changes to the Unicode NFC,
+NFKC, and NFKD normalization forms for certain Korean characters. The
+`ks_x_1026-1` crate feature (disabled by default) adds methods to support these
+alternate normalizations.
diff --git a/src/ks_x_1026_1.rs b/src/ks_x_1026_1.rs
new file mode 100644
index 0000000..dad327e
--- /dev/null
+++ b/src/ks_x_1026_1.rs
@@ -0,0 +1,233 @@
+//! <http://std.dkuug.dk/jtc1/sc2/wg2/docs/n3422.pdf> Annex B
+
+use core::{
+    convert::{TryFrom, TryInto},
+    iter::FusedIterator,
+};
+
+use tinyvec::ArrayVec;
+
+// § B.1.1
+
+use crate::normalize::hangul_constants::{
+    L_BASE, L_LAST, N_COUNT, S_BASE, S_COUNT, T_BASE, T_COUNT, T_LAST, V_BASE, V_LAST,
+};
+
+// § B.1.2
+
+fn is_old_jongseong(t: char) -> bool {
+    match t {
+        '\u{11C3}'..='\u{11FF}' | '\u{D7CB}'..='\u{D7FB}' => true,
+        _ => false,
+    }
+}
+
+/// Iterator that decomposes modern Hangul LV syllables immediately followed by old Hangul T jamo
+/// into a 3-character L V T sequences, as specified in KS X 1026-1 annex B.1.5.
+#[derive(Clone, Debug)]
+pub struct RecomposeHangul<I> {
+    /// Medial vowel of a decomposed LV syllable
+    v: Option<char>,
+    /// Character yielded by inner iterator in last call to its `next()`
+    last: Option<char>,
+    inner: I,
+}
+
+impl<I: Iterator<Item = char>> Iterator for RecomposeHangul<I> {
+    type Item = char;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if let Some(v) = self.v {
+            // If an LV syllable was decomposed in the last call to `next`,
+            // yield its medial vowel.
+            self.v = None;
+            Some(v)
+        } else {
+            let prev = self.last;
+            self.last = self.inner.next();
+
+            if let (Some(prev), Some(next)) = (prev, self.last) {
+                let s_index = u32::from(prev).wrapping_sub(S_BASE);
+                if s_index < S_COUNT && s_index % T_COUNT == 0 && is_old_jongseong(next) {
+                    // We have an LV syllable followed by an old jongseong, decompose into L V
+                    let l: char = (L_BASE + s_index / N_COUNT).try_into().unwrap();
+                    self.v = Some((V_BASE + (s_index % N_COUNT) / T_COUNT).try_into().unwrap());
+                    return Some(l);
+                }
+            }
+
+            prev
+        }
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let (inner_lo, inner_hi) = self.inner.size_hint();
+        let add_factor: usize = self.v.map_or(0, |_| 1) + self.last.map_or(0, |_| 1);
+        (
+            inner_lo.saturating_add(add_factor),
+            inner_hi
+                .and_then(|h| h.checked_mul(2))
+                .and_then(|h| h.checked_add(add_factor)),
+        )
+    }
+}
+
+impl<I: Iterator<Item = char> + FusedIterator> FusedIterator for RecomposeHangul<I> {}
+
+impl<I: Iterator<Item = char>> RecomposeHangul<I> {
+    #[inline]
+    pub(crate) fn new(mut iter: I) -> Self {
+        RecomposeHangul {
+            v: None,
+            last: iter.next(),
+            inner: iter,
+        }
+    }
+}
+
+// B.2.1
+
+static CP_JAMO: [char; 94] = [
+    '\u{1100}', '\u{1101}', '\u{11AA}', '\u{1102}', '\u{11AC}', '\u{11AD}', '\u{1103}', '\u{1104}',
+    '\u{1105}', '\u{11B0}', '\u{11B1}', '\u{11B2}', '\u{11B3}', '\u{11B4}', '\u{11B5}', '\u{111A}',
+    '\u{1106}', '\u{1107}', '\u{1108}', '\u{1121}', '\u{1109}', '\u{110A}', '\u{110B}', '\u{110C}',
+    '\u{110D}', '\u{110E}', '\u{110F}', '\u{1110}', '\u{1111}', '\u{1112}', '\u{1161}', '\u{1162}',
+    '\u{1163}', '\u{1164}', '\u{1165}', '\u{1166}', '\u{1167}', '\u{1168}', '\u{1169}', '\u{116A}',
+    '\u{116B}', '\u{116C}', '\u{116D}', '\u{116E}', '\u{116F}', '\u{1170}', '\u{1171}', '\u{1172}',
+    '\u{1173}', '\u{1174}', '\u{1175}', '\u{1160}', '\u{1114}', '\u{1115}', '\u{11C7}', '\u{11C8}',
+    '\u{11CC}', '\u{11CE}', '\u{11D3}', '\u{11D7}', '\u{11D9}', '\u{111C}', '\u{11DD}', '\u{11DF}',
+    '\u{111D}', '\u{111E}', '\u{1120}', '\u{1122}', '\u{1123}', '\u{1127}', '\u{1129}', '\u{112B}',
+    '\u{112C}', '\u{112D}', '\u{112E}', '\u{112F}', '\u{1132}', '\u{1136}', '\u{1140}', '\u{1147}',
+    '\u{114C}', '\u{11F1}', '\u{11F2}', '\u{1157}', '\u{1158}', '\u{1159}', '\u{1184}', '\u{1185}',
+    '\u{1188}', '\u{1191}', '\u{1192}', '\u{1194}', '\u{119E}', '\u{11A1}',
+];
+
+// § B.2.2
+
+static HW_JAMO: [char; 64] = [
+    '\u{1160}', '\u{1100}', '\u{1101}', '\u{11AA}', '\u{1102}', '\u{11AC}', '\u{11AD}', '\u{1103}',
+    '\u{1104}', '\u{1105}', '\u{11B0}', '\u{11B1}', '\u{11B2}', '\u{11B3}', '\u{11B4}', '\u{11B5}',
+    '\u{111A}', '\u{1106}', '\u{1107}', '\u{1108}', '\u{1121}', '\u{1109}', '\u{110A}', '\u{110B}',
+    '\u{110C}', '\u{110D}', '\u{110E}', '\u{110F}', '\u{1110}', '\u{1111}', '\u{1112}', '\u{FFBF}',
+    '\u{FFC0}', '\u{FFC1}', '\u{1161}', '\u{1162}', '\u{1163}', '\u{1164}', '\u{1165}', '\u{1166}',
+    '\u{FFC8}', '\u{FFC9}', '\u{1167}', '\u{1168}', '\u{1169}', '\u{116A}', '\u{116B}', '\u{116C}',
+    '\u{FFD0}', '\u{FFD1}', '\u{116D}', '\u{116E}', '\u{116F}', '\u{1170}', '\u{1171}', '\u{1172}',
+    '\u{FFD8}', '\u{FFD9}', '\u{1173}', '\u{1174}', '\u{1175}', '\u{FFDD}', '\u{FFDE}', '\u{FFDF}',
+];
+
+// § B.2.3
+
+static PC_JAMO: [char; 14] = [
+    '\u{1100}', '\u{1102}', '\u{1103}', '\u{1105}', '\u{1106}', '\u{1107}', '\u{1109}', '\u{110B}',
+    '\u{110C}', '\u{110E}', '\u{110F}', '\u{1110}', '\u{1111}', '\u{1112}',
+];
+
+// § B.2.4
+
+/// Iterator that decomposes compatibility characters containing Hangul jamo
+/// in a manner that avoids introducing new nonstandard jamo sequences,
+/// as specified in KS X 1026-1 annex B.2.4.
+#[derive(Clone, Debug)]
+pub struct NormalizeJamoKdkc<I> {
+    inner: I,
+    // Buffer for when a character normalizes into multiple.
+    // Characters are pushed to and popped from the end.
+    // Length 3 is sufficient, as the longest possible expansion
+    // is for a parenthesized choseong like U+3200,
+    // which expands into ['(', <choseong>, '\u{1160}', ')'] (length 4).
+    // (There are no parenthesized jungseong or jongseong.)
+    buf: ArrayVec<[char; 3]>,
+}
+
+impl<I: Iterator<Item = char>> Iterator for NormalizeJamoKdkc<I> {
+    type Item = char;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if let Some(c) = self.buf.pop() {
+            // Empty buffer before yielding from underlying iterator.
+            Some(c)
+        } else {
+            let ch = self.inner.next()?;
+            // Whether ch is a parenthesized Hangul letter
+            let mut pf = false;
+
+            let uch: u32 = ch.into();
+            let base_jamo: char = match uch {
+                // Hangul compatibility letter
+                0x3131..=0x318E => CP_JAMO[usize::try_from(uch - 0x3131).unwrap()],
+
+                // Parenthesized Hangul letter
+                0x3200..=0x320D => {
+                    pf = true;
+                    self.buf.push(')');
+                    PC_JAMO[usize::try_from(uch - 0x3200).unwrap()]
+                }
+
+                // Circled Hangul letter
+                0x3260..=0x326D => PC_JAMO[usize::try_from(uch - 0x3260).unwrap()],
+
+                // Halfwidth Hangul letter
+                0xFFA0..=0xFFDF => HW_JAMO[usize::try_from(uch - 0xFFA0).unwrap()],
+
+                _ => return Some(ch),
+            };
+
+            // Insert fillers
+            let first_ret: char = match base_jamo.into() {
+                // `base_jamo` is choseong, yield a jungseong filler after
+                L_BASE..=L_LAST => {
+                    self.buf.push('\u{1160}');
+                    base_jamo
+                }
+
+                // `base_jamo` is jungseong, yield a choseong filler before
+                V_BASE..=V_LAST => {
+                    self.buf.push(base_jamo);
+                    '\u{115F}'
+                }
+
+                // `base_jamo` is jongseong, yield a choseong and a jungseong filler before
+                T_BASE..=T_LAST => {
+                    self.buf.push(base_jamo);
+                    self.buf.push('\u{1160}');
+                    '\u{115F}'
+                }
+
+                _ => unreachable!("`base_jamo` shluld be a jamo, but is not"),
+            };
+
+            if pf {
+                // Parenthesized Hangul letter, yield open paren before
+                self.buf.push(first_ret);
+                Some('(')
+            } else {
+                Some(first_ret)
+            }
+        }
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let (inner_lo, inner_hi) = self.inner.size_hint();
+        let add_factor: usize = self.buf.len();
+        (
+            inner_lo.saturating_add(add_factor),
+            inner_hi
+                .and_then(|h| h.checked_mul(4)) // Why 4? See comment on `buf` field
+                .and_then(|h| h.checked_add(add_factor)),
+        )
+    }
+}
+
+impl<I: Iterator<Item = char> + FusedIterator> FusedIterator for NormalizeJamoKdkc<I> {}
+
+impl<I: Iterator<Item = char>> NormalizeJamoKdkc<I> {
+    #[inline]
+    pub(crate) fn new(iter: I) -> Self {
+        NormalizeJamoKdkc {
+            inner: iter,
+            buf: ArrayVec::new(),
+        }
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index cc0a850..32ef120 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -36,23 +36,36 @@
 //! [dependencies]
 //! unicode-normalization = "0.1.20"
 //! ```
+//!
+//! # KS X 1026-1
+//!
+//! Korean Standard KS X 1026-1 ([Korean](https://standard.go.kr/KSCI/standardIntro/getStandardSearchView.do?ksNo=KSX1026-1),
+//! [English](http://std.dkuug.dk/jtc1/sc2/wg2/docs/n3422.pdf)) is an ROK government
+//! standard that corrects some defects and makes some changes to the Unicode NFC,
+//! NFKC, and NFKD normalization forms for certain Korean characters. The
+//! `ks_x_1026-1` crate feature (disabled by default) adds methods to support these
+//! alternate normalizations.
 
 #![deny(missing_docs, unsafe_code)]
 #![doc(
     html_logo_url = "https://unicode-rs.github.io/unicode-rs_sm.png",
     html_favicon_url = "https://unicode-rs.github.io/unicode-rs_sm.png"
 )]
+#![cfg_attr(docsrs, feature(doc_cfg))]
 #![cfg_attr(not(feature = "std"), no_std)]
 
 #[cfg(not(feature = "std"))]
 extern crate alloc;
 
-#[cfg(feature = "std")]
-extern crate core;
-
 extern crate tinyvec;
 
 pub use crate::decompose::Decompositions;
+#[cfg(feature = "ks_x_1026-1")]
+#[cfg_attr(docsrs, doc(cfg(feature = "ks_x_1026-1")))]
+pub use crate::ks_x_1026_1::NormalizeJamoKdkc;
+#[cfg(feature = "ks_x_1026-1")]
+#[cfg_attr(docsrs, doc(cfg(feature = "ks_x_1026-1")))]
+pub use crate::ks_x_1026_1::RecomposeHangul;
 pub use crate::quick_check::{
     is_nfc, is_nfc_quick, is_nfc_stream_safe, is_nfc_stream_safe_quick, is_nfd, is_nfd_quick,
     is_nfd_stream_safe, is_nfd_stream_safe_quick, is_nfkc, is_nfkc_quick, is_nfkd, is_nfkd_quick,
@@ -65,6 +78,8 @@ pub use crate::tables::UNICODE_VERSION;
 use core::{option, str::Chars};
 
 mod decompose;
+#[cfg(feature = "ks_x_1026-1")]
+mod ks_x_1026_1;
 mod lookups;
 mod normalize;
 mod perfect_hash;
@@ -97,19 +112,19 @@ pub mod char {
 /// as described in
 /// [Unicode Standard Annex #15](http://www.unicode.org/reports/tr15/).
 pub trait UnicodeNormalization<I: Iterator<Item = char>> {
-    /// Returns an iterator over the string in Unicode Normalization Form D
+    /// An iterator over the string in Unicode Normalization Form D
     /// (canonical decomposition).
     fn nfd(self) -> Decompositions<I>;
 
-    /// Returns an iterator over the string in Unicode Normalization Form KD
+    /// An iterator over the string in Unicode Normalization Form KD
     /// (compatibility decomposition).
     fn nfkd(self) -> Decompositions<I>;
 
-    /// An Iterator over the string in Unicode Normalization Form C
+    /// An iterator over the string in Unicode Normalization Form C
     /// (canonical decomposition followed by canonical composition).
     fn nfc(self) -> Recompositions<I>;
 
-    /// An Iterator over the string in Unicode Normalization Form KC
+    /// An iterator over the string in Unicode Normalization Form KC
     /// (compatibility decomposition followed by canonical composition).
     fn nfkc(self) -> Recompositions<I>;
 
@@ -125,9 +140,41 @@ pub trait UnicodeNormalization<I: Iterator<Item = char>> {
     /// implementations the option to recognize them.
     fn cjk_compat_variants(self) -> Replacements<I>;
 
-    /// An Iterator over the string with Conjoining Grapheme Joiner characters
-    /// inserted according to the Stream-Safe Text Process (UAX15-D4)
+    /// An iterator over the string with Conjoining Grapheme Joiner characters
+    /// inserted according to the Stream-Safe Text Process ([UAX15-D4](https://unicode.org/reports/tr15/#UAX15-D4))
     fn stream_safe(self) -> StreamSafe<I>;
+
+    /// An iterator over the string in the variant of Unicode Normalization Form KD
+    /// defined by Korean Standard X 1026-1. This normalization differs from that defined by Unicode
+    /// in that it will not produce nonstandard Korean jamo sequences if none were present in the input.
+    /// (Any string that is in KS X 1026-1 modified NFKD is also in standard Unicode NFKD,
+    /// but the reverse may not hold.)
+    #[cfg(feature = "ks_x_1026-1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "ks_x_1026-1")))]
+
+    fn nfkd_ks_x_1026_1(self) -> Decompositions<NormalizeJamoKdkc<I>>;
+
+    /// An iterator over the string in the variant of Unicode Normalization Form C
+    /// defined by Korean Standard X 1026-1. This normalization differs from that defined by Unicode
+    /// in that it will not contain any precomposed LV Hangul syllables immediately followed by conjoining T jamo.
+    /// (A string that is in KS X 1026-1 modified NFC might not be in standard Unicode NFC,
+    /// and vice versa.)
+    #[cfg(feature = "ks_x_1026-1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "ks_x_1026-1")))]
+
+    fn nfc_ks_x_1026_1(self) -> RecomposeHangul<Recompositions<I>>;
+
+    /// An iterator over the string in the variant of Unicode Normalization Form KC
+    /// defined by Korean Standard X 1026-1. This normalization differs from that defined by Unicode
+    /// in that it will not produce nonstandard Korean jamo sequences if none were present in the input,
+    /// and it will also not contain any precomposed LV Hangul syllables immediately followed
+    /// by conjoining T jamo.
+    /// (A string that is in KS X 1026-1 modified NFKC might not be in standard Unicode NFKC,
+    /// and vice versa.)
+    #[cfg(feature = "ks_x_1026-1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "ks_x_1026-1")))]
+
+    fn nfkc_ks_x_1026_1(self) -> RecomposeHangul<Recompositions<NormalizeJamoKdkc<I>>>;
 }
 
 impl<'a> UnicodeNormalization<Chars<'a>> for &'a str {
@@ -160,6 +207,29 @@ impl<'a> UnicodeNormalization<Chars<'a>> for &'a str {
     fn stream_safe(self) -> StreamSafe<Chars<'a>> {
         StreamSafe::new(self.chars())
     }
+
+    #[cfg(feature = "ks_x_1026-1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "ks_x_1026-1")))]
+    #[inline]
+    fn nfkd_ks_x_1026_1(self) -> Decompositions<NormalizeJamoKdkc<Chars<'a>>> {
+        decompose::new_compatible(NormalizeJamoKdkc::new(self.chars()))
+    }
+
+    #[cfg(feature = "ks_x_1026-1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "ks_x_1026-1")))]
+    #[inline]
+    fn nfc_ks_x_1026_1(self) -> RecomposeHangul<Recompositions<Chars<'a>>> {
+        RecomposeHangul::new(self.nfc())
+    }
+
+    #[cfg(feature = "ks_x_1026-1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "ks_x_1026-1")))]
+    #[inline]
+    fn nfkc_ks_x_1026_1(self) -> RecomposeHangul<Recompositions<NormalizeJamoKdkc<Chars<'a>>>> {
+        RecomposeHangul::new(recompose::new_compatible(NormalizeJamoKdkc::new(
+            self.chars(),
+        )))
+    }
 }
 
 impl UnicodeNormalization<option::IntoIter<char>> for char {
@@ -192,6 +262,31 @@ impl UnicodeNormalization<option::IntoIter<char>> for char {
     fn stream_safe(self) -> StreamSafe<option::IntoIter<char>> {
         StreamSafe::new(Some(self).into_iter())
     }
+
+    #[cfg(feature = "ks_x_1026-1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "ks_x_1026-1")))]
+    #[inline]
+    fn nfkd_ks_x_1026_1(self) -> Decompositions<NormalizeJamoKdkc<option::IntoIter<char>>> {
+        decompose::new_compatible(NormalizeJamoKdkc::new(Some(self).into_iter()))
+    }
+
+    #[cfg(feature = "ks_x_1026-1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "ks_x_1026-1")))]
+    #[inline]
+    fn nfc_ks_x_1026_1(self) -> RecomposeHangul<Recompositions<option::IntoIter<char>>> {
+        RecomposeHangul::new(self.nfc())
+    }
+
+    #[cfg(feature = "ks_x_1026-1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "ks_x_1026-1")))]
+    #[inline]
+    fn nfkc_ks_x_1026_1(
+        self,
+    ) -> RecomposeHangul<Recompositions<NormalizeJamoKdkc<option::IntoIter<char>>>> {
+        RecomposeHangul::new(recompose::new_compatible(NormalizeJamoKdkc::new(
+            Some(self).into_iter(),
+        )))
+    }
 }
 
 impl<I: Iterator<Item = char>> UnicodeNormalization<I> for I {
@@ -224,4 +319,25 @@ impl<I: Iterator<Item = char>> UnicodeNormalization<I> for I {
     fn stream_safe(self) -> StreamSafe<I> {
         StreamSafe::new(self)
     }
+
+    #[cfg(feature = "ks_x_1026-1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "ks_x_1026-1")))]
+    #[inline]
+    fn nfkd_ks_x_1026_1(self) -> Decompositions<NormalizeJamoKdkc<I>> {
+        decompose::new_compatible(NormalizeJamoKdkc::new(self))
+    }
+
+    #[cfg(feature = "ks_x_1026-1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "ks_x_1026-1")))]
+    #[inline]
+    fn nfc_ks_x_1026_1(self) -> RecomposeHangul<Recompositions<I>> {
+        RecomposeHangul::new(self.nfc())
+    }
+
+    #[cfg(feature = "ks_x_1026-1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "ks_x_1026-1")))]
+    #[inline]
+    fn nfkc_ks_x_1026_1(self) -> RecomposeHangul<Recompositions<NormalizeJamoKdkc<I>>> {
+        RecomposeHangul::new(recompose::new_compatible(NormalizeJamoKdkc::new(self)))
+    }
 }
diff --git a/src/normalize.rs b/src/normalize.rs
index e878642..b742927 100644
--- a/src/normalize.rs
+++ b/src/normalize.rs
@@ -106,22 +106,27 @@ pub fn compose(a: char, b: char) -> Option<char> {
     compose_hangul(a, b).or_else(|| composition_table(a, b))
 }
 
-// Constants from Unicode 9.0.0 Section 3.12 Conjoining Jamo Behavior
-// http://www.unicode.org/versions/Unicode9.0.0/ch03.pdf#M9.32468.Heading.310.Combining.Jamo.Behavior
-const S_BASE: u32 = 0xAC00;
-const L_BASE: u32 = 0x1100;
-const V_BASE: u32 = 0x1161;
-const T_BASE: u32 = 0x11A7;
-const L_COUNT: u32 = 19;
-const V_COUNT: u32 = 21;
-const T_COUNT: u32 = 28;
-const N_COUNT: u32 = V_COUNT * T_COUNT;
-const S_COUNT: u32 = L_COUNT * N_COUNT;
-
-const S_LAST: u32 = S_BASE + S_COUNT - 1;
-const L_LAST: u32 = L_BASE + L_COUNT - 1;
-const V_LAST: u32 = V_BASE + V_COUNT - 1;
-const T_LAST: u32 = T_BASE + T_COUNT - 1;
+/// Constants from Unicode 15.0.0 Section 3.12 Conjoining Jamo Behavior
+/// <http://www.unicode.org/versions/Unicode15.0.0/ch03.pdf#M9.32468.Heading.310.Combining.Jamo.Behavior>
+/// (also found in KS X 1026-1 annex B.1.1 <http://std.dkuug.dk/jtc1/sc2/wg2/docs/n3422.pdf>).
+pub mod hangul_constants {
+    pub const S_BASE: u32 = 0xAC00;
+    pub const L_BASE: u32 = 0x1100;
+    pub const V_BASE: u32 = 0x1161;
+    pub const T_BASE: u32 = 0x11A7;
+    pub const L_COUNT: u32 = 19;
+    pub const V_COUNT: u32 = 21;
+    pub const T_COUNT: u32 = 28;
+    pub const N_COUNT: u32 = V_COUNT * T_COUNT;
+    pub const S_COUNT: u32 = L_COUNT * N_COUNT;
+
+    pub const S_LAST: u32 = S_BASE + S_COUNT - 1;
+    pub const L_LAST: u32 = L_BASE + L_COUNT - 1;
+    pub const V_LAST: u32 = V_BASE + V_COUNT - 1;
+    pub const T_LAST: u32 = T_BASE + T_COUNT - 1;
+}
+
+use hangul_constants::*;
 
 // Composition only occurs for `TPart`s in `U+11A8 ..= U+11C2`,
 // i.e. `T_BASE + 1 ..= T_LAST`.
diff --git a/tests/ks_x_1026_1.rs b/tests/ks_x_1026_1.rs
new file mode 100644
index 0000000..55dc81c
--- /dev/null
+++ b/tests/ks_x_1026_1.rs
@@ -0,0 +1,103 @@
+#![cfg(feature = "ks_x_1026-1")]
+
+use unicode_normalization::UnicodeNormalization;
+
+macro_rules! norm_string {
+    ($method: ident, $input: expr) => {
+        $input.$method().collect::<String>()
+    };
+}
+
+/// § 6.2
+#[test]
+fn compatibility_and_halfwidth_hangul_letters() {
+    // Compatibility
+    let orig = "\u{3131}\u{314F}";
+    assert_eq!(norm_string!(nfkd, orig), "\u{1100}\u{1161}");
+    assert_eq!(norm_string!(nfkc, orig), "\u{AC00}");
+    assert_eq!(
+        norm_string!(nfkd_ks_x_1026_1, orig),
+        "\u{1100}\u{1160}\u{115F}\u{1161}"
+    );
+    assert_eq!(
+        norm_string!(nfkc_ks_x_1026_1, orig),
+        "\u{1100}\u{1160}\u{115F}\u{1161}"
+    );
+
+    // Halfwidth
+    let orig = "\u{FFA1}\u{FFC6}";
+    assert_eq!(norm_string!(nfd, orig), "\u{FFA1}\u{FFC6}");
+    assert_eq!(norm_string!(nfc, orig), "\u{FFA1}\u{FFC6}");
+    assert_eq!(norm_string!(nfkd, orig), "\u{1100}\u{1165}");
+    assert_eq!(norm_string!(nfkc, orig), "\u{AC70}");
+    assert_eq!(norm_string!(nfc_ks_x_1026_1, orig), "\u{FFA1}\u{FFC6}");
+    assert_eq!(
+        norm_string!(nfkd_ks_x_1026_1, orig),
+        "\u{1100}\u{1160}\u{115F}\u{1165}"
+    );
+    assert_eq!(
+        norm_string!(nfkc_ks_x_1026_1, orig),
+        "\u{1100}\u{1160}\u{115F}\u{1165}"
+    );
+}
+
+/// § 6.3
+#[test]
+fn hangul_embedded_symbols() {
+    // Circled
+    let orig = "\u{3260}";
+    assert_eq!(norm_string!(nfd, orig), "\u{3260}");
+    assert_eq!(norm_string!(nfc, orig), "\u{3260}");
+    assert_eq!(norm_string!(nfkd, orig), "\u{1100}");
+    assert_eq!(norm_string!(nfkc, orig), "\u{1100}");
+    assert_eq!(norm_string!(nfc_ks_x_1026_1, orig), "\u{3260}");
+    assert_eq!(norm_string!(nfkd_ks_x_1026_1, orig), "\u{1100}\u{1160}");
+    assert_eq!(norm_string!(nfkc_ks_x_1026_1, orig), "\u{1100}\u{1160}");
+
+    // Parenthesized
+    let orig = "\u{3200}";
+    assert_eq!(norm_string!(nfd, orig), "\u{3200}");
+    assert_eq!(norm_string!(nfc, orig), "\u{3200}");
+    assert_eq!(norm_string!(nfkd, orig), "(\u{1100})");
+    assert_eq!(norm_string!(nfkc, orig), "(\u{1100})");
+    assert_eq!(norm_string!(nfc_ks_x_1026_1, orig), "\u{3200}");
+    assert_eq!(norm_string!(nfkd_ks_x_1026_1, orig), "(\u{1100}\u{1160})");
+    assert_eq!(norm_string!(nfkc_ks_x_1026_1, orig), "(\u{1100}\u{1160})");
+}
+
+/// § 6.4
+#[test]
+fn hangul_syllable_blocks() {
+    let orig = "\u{1100}\u{1161}\u{11EB}";
+    assert_eq!(norm_string!(nfd, orig), "\u{1100}\u{1161}\u{11EB}");
+    assert_eq!(norm_string!(nfc, orig), "\u{AC00}\u{11EB}");
+    assert_eq!(norm_string!(nfkd, orig), "\u{1100}\u{1161}\u{11EB}");
+    assert_eq!(norm_string!(nfkc, orig), "\u{AC00}\u{11EB}");
+    assert_eq!(
+        norm_string!(nfc_ks_x_1026_1, orig),
+        "\u{1100}\u{1161}\u{11EB}"
+    );
+    assert_eq!(
+        norm_string!(nfkd_ks_x_1026_1, orig),
+        "\u{1100}\u{1161}\u{11EB}"
+    );
+    assert_eq!(
+        norm_string!(nfkc_ks_x_1026_1, orig),
+        "\u{1100}\u{1161}\u{11EB}"
+    );
+}
+
+#[test]
+fn non_hangul() {
+    let orig = "ab\u{010D}de\u{0301}";
+    assert_eq!(norm_string!(nfd, orig), "abc\u{030C}de\u{0301}");
+    assert_eq!(norm_string!(nfc, orig), "ab\u{010D}d\u{00E9}");
+    assert_eq!(norm_string!(nfkd, orig), "abc\u{030C}de\u{0301}");
+    assert_eq!(norm_string!(nfkc, orig), "ab\u{010D}d\u{00E9}");
+    assert_eq!(norm_string!(nfc_ks_x_1026_1, orig), "ab\u{010D}d\u{00E9}");
+    assert_eq!(
+        norm_string!(nfkd_ks_x_1026_1, orig),
+        "abc\u{030C}de\u{0301}"
+    );
+    assert_eq!(norm_string!(nfkc_ks_x_1026_1, orig), "ab\u{010D}d\u{00E9}");
+}