diff --git a/CHANGELOG.md b/CHANGELOG.md
index caa6ac2..29892dd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@
  * Internal performance improvements for up to 10% faster tree building by avoiding unnecessary duplication of elements.
  * Use `NonNull` for the internal representation of `SyntaxNode`, meaning it now benefits from niche optimizations (`Option<SyntaxNode>` is now the same size as `SyntaxNode` itself: the size of a pointer).
  * `SyntaxKind` has been renamed to `RawSyntaxKind` to no longer conflict with user-defined `SyntaxKind` enumerations.
+   * `RawSyntaxKind` has been changed to use a 32-bit index internally, which means existing `Language` implementations and syntax kind `enum`s need to be adjusted to `#[repr(u32)]` and the corresponding conversions.
  * The crate's export module structure has been reorganized to give different groups of definitions their own submodules. A `cstree::prelude` module is available, containing the most commonly needed types that were previously accessible via `use cstree::*`. Otherwise, the module structure is now as follows:
    * `cstree`
      * `Language`
diff --git a/benches/main.rs b/benches/main.rs
index f1373b5..3f95608 100644
--- a/benches/main.rs
+++ b/benches/main.rs
@@ -16,7 +16,7 @@ pub enum Element<'s> {
 
 #[derive(Debug, Clone, Copy)]
 pub enum TestKind {
-    Element { n: u16 },
+    Element { n: u32 },
     Plus,
 }
 
@@ -45,7 +45,7 @@ impl<T: Bool> Language for TestLang<T> {
     type Kind = TestKind;
 
     fn kind_from_raw(raw: RawSyntaxKind) -> Self::Kind {
-        if raw.0 == u16::MAX - 1 {
+        if raw.0 == u32::MAX - 1 {
             TestKind::Plus
         } else {
             TestKind::Element { n: raw.0 }
@@ -55,7 +55,7 @@ impl<T: Bool> Language for TestLang<T> {
     fn kind_to_raw(kind: Self::Kind) -> RawSyntaxKind {
         match kind {
             TestKind::Element { n } => RawSyntaxKind(n),
-            TestKind::Plus => RawSyntaxKind(u16::MAX - 1),
+            TestKind::Plus => RawSyntaxKind(u32::MAX - 1),
         }
     }
 
@@ -85,8 +85,8 @@ where
 pub fn build_recursive<T: Bool, I>(
     root: &Element<'_>,
     builder: &mut GreenNodeBuilder<'_, '_, TestLang<T>, I>,
-    mut from: u16,
-) -> u16
+    mut from: u32,
+) -> u32
 where
     I: Interner,
 {
diff --git a/examples/math.rs b/examples/math.rs
index e2346ac..3b00957 100644
--- a/examples/math.rs
+++ b/examples/math.rs
@@ -17,7 +17,7 @@ use cstree::{build::GreenNodeBuilder, interning::Resolver, util::NodeOrToken};
 use std::iter::Peekable;
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-#[repr(u16)]
+#[repr(u32)]
 enum SyntaxKind {
     Whitespace = 0,
 
@@ -35,7 +35,7 @@ use SyntaxKind::*;
 
 impl From<SyntaxKind> for cstree::RawSyntaxKind {
     fn from(kind: SyntaxKind) -> Self {
-        Self(kind as u16)
+        Self(kind as u32)
     }
 }
 
@@ -45,8 +45,8 @@ impl cstree::Language for Lang {
     type Kind = SyntaxKind;
 
     fn kind_from_raw(raw: cstree::RawSyntaxKind) -> Self::Kind {
-        assert!(raw.0 <= Root as u16);
-        unsafe { std::mem::transmute::<u16, SyntaxKind>(raw.0) }
+        assert!(raw.0 <= Root as u32);
+        unsafe { std::mem::transmute::<u32, SyntaxKind>(raw.0) }
     }
 
     fn kind_to_raw(kind: Self::Kind) -> cstree::RawSyntaxKind {
diff --git a/examples/readme.rs b/examples/readme.rs
index 6e3890d..ff0f083 100644
--- a/examples/readme.rs
+++ b/examples/readme.rs
@@ -7,7 +7,7 @@ use cstree::{
 };
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-#[repr(u16)]
+#[repr(u32)]
 pub enum SyntaxKind {
     /* Tokens */
     Int,    // 42
@@ -42,7 +42,7 @@ impl Language for Calculator {
     }
 
     fn kind_to_raw(kind: Self::Kind) -> RawSyntaxKind {
-        RawSyntaxKind(kind as u16)
+        RawSyntaxKind(kind as u32)
     }
 
     fn static_text(kind: Self::Kind) -> Option<&'static str> {
diff --git a/examples/s_expressions.rs b/examples/s_expressions.rs
index bed6832..3311150 100644
--- a/examples/s_expressions.rs
+++ b/examples/s_expressions.rs
@@ -9,7 +9,7 @@
 
 /// Let's start with defining all kinds of tokens and composite nodes.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-#[repr(u16)]
+#[repr(u32)]
 pub enum SyntaxKind {
     LParen = 0, // '('
     RParen,     // ')'
@@ -32,7 +32,7 @@ use SyntaxKind::*;
 /// First, to easily pass the enum variants into cstree via `.into()`:
 impl From<SyntaxKind> for cstree::RawSyntaxKind {
     fn from(kind: SyntaxKind) -> Self {
-        Self(kind as u16)
+        Self(kind as u32)
     }
 }
 
@@ -45,8 +45,8 @@ impl cstree::Language for Lang {
     type Kind = SyntaxKind;
 
     fn kind_from_raw(raw: cstree::RawSyntaxKind) -> Self::Kind {
-        assert!(raw.0 <= Root as u16);
-        unsafe { std::mem::transmute::<u16, SyntaxKind>(raw.0) }
+        assert!(raw.0 <= Root as u32);
+        unsafe { std::mem::transmute::<u32, SyntaxKind>(raw.0) }
     }
 
     fn kind_to_raw(kind: Self::Kind) -> cstree::RawSyntaxKind {
@@ -421,7 +421,7 @@ nan
 /// Split the input string into a flat list of tokens (such as L_PAREN, WORD, and WHITESPACE)
 fn lex(text: &str) -> VecDeque<(SyntaxKind, &str)> {
     fn tok(t: SyntaxKind) -> m_lexer::TokenKind {
-        m_lexer::TokenKind(cstree::RawSyntaxKind::from(t).0)
+        m_lexer::TokenKind(cstree::RawSyntaxKind::from(t).0 as u16)
     }
     fn kind(t: m_lexer::TokenKind) -> SyntaxKind {
         match t.0 {
diff --git a/src/lib.rs b/src/lib.rs
index dfa934b..41d33f2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -58,12 +58,12 @@
 //!
 //! First, we need to list the different part of our language's grammar.
 //! We can do that using an `enum` with a unit variant for any terminal and non-terminal.
-//! The `enum` needs to be convertible to a `u16`, so we use the `repr` attribute to ensure it uses the correct
+//! The `enum` needs to be convertible to a `u32`, so we use the `repr` attribute to ensure it uses the correct
 //! representation.
 //!
 //! ```rust,ignore
 //! #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-//! #[repr(u16)]
+//! #[repr(u32)]
 //! enum SyntaxKind {
 //!     /* Tokens */
 //!     Int,    // 42
@@ -112,7 +112,7 @@
 //!     }
 //!
 //!     fn kind_to_raw(kind: Self::Kind) -> RawSyntaxKind {
-//!         RawSyntaxKind(kind as u16)
+//!         RawSyntaxKind(kind as u32)
 //!     }
 //!
 //!     fn static_text(kind: Self::Kind) -> Option<&'static str> {
@@ -368,7 +368,7 @@ use std::fmt;
 
 /// `RawSyntaxKind` is a type tag for each token or node.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub struct RawSyntaxKind(pub u16);
+pub struct RawSyntaxKind(pub u32);
 
 /// Typesafe representations of text ranges and sizes.
 pub mod text {
@@ -423,7 +423,7 @@ pub mod sync {
 /// ```
 /// #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 /// # #[allow(non_camel_case_types)]
-/// #[repr(u16)]
+/// #[repr(u32)]
 /// enum SyntaxKind {
 ///     Plus,       // `+`
 ///     Minus,      // `-`
@@ -442,12 +442,12 @@ pub mod sync {
 ///     type Kind = SyntaxKind;
 ///
 ///     fn kind_from_raw(raw: cstree::RawSyntaxKind) -> Self::Kind {
-///         assert!(raw.0 <= __LAST as u16);
-///         unsafe { std::mem::transmute::<u16, SyntaxKind>(raw.0) }
+///         assert!(raw.0 <= __LAST as u32);
+///         unsafe { std::mem::transmute::<u32, SyntaxKind>(raw.0) }
 ///     }
 ///
 ///     fn kind_to_raw(kind: Self::Kind) -> cstree::RawSyntaxKind {
-///         cstree::RawSyntaxKind(kind as u16)
+///         cstree::RawSyntaxKind(kind as u32)
 ///     }
 ///
 ///     fn static_text(kind: Self::Kind) -> Option<&'static str> {
@@ -489,7 +489,7 @@ pub mod testing {
     pub fn parse<L: Language, I>(_b: &mut GreenNodeBuilder<L, I>, _s: &str) {}
 
     #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-    #[repr(u16)]
+    #[repr(u32)]
     #[allow(non_camel_case_types)]
     pub enum TestSyntaxKind {
         Plus,
@@ -510,12 +510,12 @@ pub mod testing {
         type Kind = TestSyntaxKind;
 
         fn kind_from_raw(raw: RawSyntaxKind) -> Self::Kind {
-            assert!(raw.0 <= TestSyntaxKind::__LAST as u16);
-            unsafe { std::mem::transmute::<u16, TestSyntaxKind>(raw.0) }
+            assert!(raw.0 <= TestSyntaxKind::__LAST as u32);
+            unsafe { std::mem::transmute::<u32, TestSyntaxKind>(raw.0) }
         }
 
         fn kind_to_raw(kind: Self::Kind) -> RawSyntaxKind {
-            RawSyntaxKind(kind as u16)
+            RawSyntaxKind(kind as u32)
         }
 
         fn static_text(kind: Self::Kind) -> Option<&'static str> {
diff --git a/src/serde_impls.rs b/src/serde_impls.rs
index ecf0731..daa8ffb 100644
--- a/src/serde_impls.rs
+++ b/src/serde_impls.rs
@@ -244,7 +244,7 @@ impl Serialize for RawSyntaxKind {
     where
         S: serde::Serializer,
     {
-        serializer.serialize_u16(self.0)
+        serializer.serialize_u32(self.0)
     }
 }
 
@@ -253,6 +253,6 @@ impl<'de> Deserialize<'de> for RawSyntaxKind {
     where
         D: serde::Deserializer<'de>,
     {
-        Ok(Self(u16::deserialize(deserializer)?))
+        Ok(Self(u32::deserialize(deserializer)?))
     }
 }
diff --git a/src/syntax/mod.rs b/src/syntax/mod.rs
index dd274eb..e275c04 100644
--- a/src/syntax/mod.rs
+++ b/src/syntax/mod.rs
@@ -61,7 +61,9 @@ mod tests {
         use std::mem::size_of;
 
         assert_eq!(size_of::<SyntaxNode<TestLang>>(),          size_of::<*const u8>());
-        assert_eq!(size_of::<Option<SyntaxNode<TestLang>>>(),  size_of::<*const u8>()); // verify niche opt of `NonNull`
-        assert_eq!(size_of::<SyntaxToken<TestLang>>(),         size_of::<*const u8>() + size_of::<u32>() * 2);
+        // verify niche opt of `NonNull`
+        assert_eq!(size_of::<Option<SyntaxNode<TestLang>>>(),  size_of::<*const u8>()); 
+        // parent + child index + text len
+        assert_eq!(size_of::<SyntaxToken<TestLang>>(),         size_of::<SyntaxNode<TestLang>>() + size_of::<u32>() * 2);
     }
 }
diff --git a/tests/it/main.rs b/tests/it/main.rs
index c3777c3..256856f 100644
--- a/tests/it/main.rs
+++ b/tests/it/main.rs
@@ -56,7 +56,7 @@ where
     node
 }
 
-pub fn build_recursive<L, I>(root: &Element<'_>, builder: &mut GreenNodeBuilder<'_, '_, L, I>, mut from: u16) -> u16
+pub fn build_recursive<L, I>(root: &Element<'_>, builder: &mut GreenNodeBuilder<'_, '_, L, I>, mut from: u32) -> u32
 where
     L: Language<Kind = RawSyntaxKind>,
     I: Interner,
diff --git a/tests/it/regressions.rs b/tests/it/regressions.rs
index 12d5294..d65aebd 100644
--- a/tests/it/regressions.rs
+++ b/tests/it/regressions.rs
@@ -6,7 +6,7 @@ fn empty_tree_arc() {
     use cstree::{build::GreenNodeBuilder, syntax::SyntaxNode};
     #[allow(non_camel_case_types)]
     #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-    #[repr(u16)]
+    #[repr(u32)]
     enum SyntaxKind {
         Root,
     }
@@ -17,12 +17,12 @@ fn empty_tree_arc() {
         type Kind = SyntaxKind;
 
         fn kind_from_raw(raw: cstree::RawSyntaxKind) -> Self::Kind {
-            assert!(raw.0 <= SyntaxKind::Root as u16);
-            unsafe { std::mem::transmute::<u16, SyntaxKind>(raw.0) }
+            assert!(raw.0 <= SyntaxKind::Root as u32);
+            unsafe { std::mem::transmute::<u32, SyntaxKind>(raw.0) }
         }
 
         fn kind_to_raw(kind: Self::Kind) -> cstree::RawSyntaxKind {
-            cstree::RawSyntaxKind(kind as u16)
+            cstree::RawSyntaxKind(kind as u32)
         }
 
         fn static_text(_kind: Self::Kind) -> Option<&'static str> {
diff --git a/tests/it/serde.rs b/tests/it/serde.rs
index f8432b2..7f7e42e 100644
--- a/tests/it/serde.rs
+++ b/tests/it/serde.rs
@@ -26,7 +26,7 @@ macro_rules! event_tokens {
             Token::BorrowedStr("Token"),
             Token::BorrowedStr("c"),
             Token::Tuple { len: 2 },
-            Token::U16($kind),
+            Token::U32($kind),
             Token::BorrowedStr($str),
             Token::TupleEnd,
             Token::StructEnd,
@@ -40,7 +40,7 @@ macro_rules! event_tokens {
             Token::BorrowedStr("EnterNode"),
             Token::BorrowedStr("c"),
             Token::Tuple { len: 2 },
-            Token::U16($kind),
+            Token::U32($kind),
             Token::Bool($data),
             Token::TupleEnd,
             Token::StructEnd,