diff --git a/Sources/MarkdownView/Contents/ListItemContent.swift b/Sources/MarkdownView/Contents/ListItemContent.swift
index 8c86d58..da5aca7 100644
--- a/Sources/MarkdownView/Contents/ListItemContent.swift
+++ b/Sources/MarkdownView/Contents/ListItemContent.swift
@@ -18,4 +18,4 @@ public struct ListItemContent: Hashable, Sendable {
   }
 }
 
-extension Checkbox: @unchecked Sendable {}
+extension Checkbox: @unchecked @retroactive Sendable {}
diff --git a/Sources/MarkdownView/Contents/MarkupContent.swift b/Sources/MarkdownView/Contents/MarkupContent.swift
index 483d5ea..cd80bdc 100644
--- a/Sources/MarkdownView/Contents/MarkupContent.swift
+++ b/Sources/MarkdownView/Contents/MarkupContent.swift
@@ -30,4 +30,4 @@ public enum MarkupContent: Hashable, Sendable {
   case unhandled(content: String)
 }
 
-extension Aside.Kind: @unchecked Sendable, Hashable {}
+extension Aside.Kind: @unchecked @retroactive Sendable, @retroactive Hashable {}