diff --git a/Sources/SwiftSyntax/SyntaxChildren.swift b/Sources/SwiftSyntax/SyntaxChildren.swift
index ffe67a40bdf..893ccb56fe0 100644
--- a/Sources/SwiftSyntax/SyntaxChildren.swift
+++ b/Sources/SwiftSyntax/SyntaxChildren.swift
@@ -14,7 +14,7 @@
 
 /// The data for an index in a syntax children collection that is not the end
 /// index. See ``SyntaxChildrenIndex`` for the representation of the end index.
-struct SyntaxChildrenIndexData: Hashable, Comparable {
+struct SyntaxChildrenIndexData: Hashable, Comparable, Sendable {
   /// The UTF-8 offset of the item at this index in the source file
   /// See `AbsoluteSyntaxPosition.offset`
   let offset: UInt32
@@ -50,7 +50,7 @@ struct SyntaxChildrenIndexData: Hashable, Comparable {
 }
 
 /// An index in a syntax children collection.
-public struct SyntaxChildrenIndex: Hashable, Comparable, ExpressibleByNilLiteral {
+public struct SyntaxChildrenIndex: Hashable, Comparable, ExpressibleByNilLiteral, Sendable {
   /// Construct the `endIndex` of a ``SyntaxChildren`` collection.
   public init(nilLiteral: ()) {
     self.data = nil
diff --git a/Sources/SwiftSyntax/SyntaxIdentifier.swift b/Sources/SwiftSyntax/SyntaxIdentifier.swift
index 6886c6bfe3f..8f3c297cf16 100644
--- a/Sources/SwiftSyntax/SyntaxIdentifier.swift
+++ b/Sources/SwiftSyntax/SyntaxIdentifier.swift
@@ -12,7 +12,7 @@
 
 /// Represents a unique value for a node within its own tree.
 @_spi(RawSyntax)
-public struct SyntaxIndexInTree: Comparable, Hashable {
+public struct SyntaxIndexInTree: Comparable, Hashable, Sendable {
   let indexInTree: UInt32
 
   static var zero: SyntaxIndexInTree = SyntaxIndexInTree(indexInTree: 0)