diff --git a/Sources/MarkdownUI/Utility/ResizeToFit.swift b/Sources/MarkdownUI/Utility/ResizeToFit.swift
index 4029ce06..918a048d 100644
--- a/Sources/MarkdownUI/Utility/ResizeToFit.swift
+++ b/Sources/MarkdownUI/Utility/ResizeToFit.swift
@@ -34,8 +34,9 @@ private struct ResizeToFit1<Content>: View where Content: View {
         .preference(key: SizePreference.self, value: size)
     }
     .frame(width: size?.width, height: size?.height)
-    .onPreferenceChange(SizePreference.self) { size in
-      self.size = size
+    .onPreferenceChange(SizePreference.self) { [$size] size in
+      // Roundabout capture makes closure sendable (see #389)
+      $size.wrappedValue = size
     }
   }
 
diff --git a/Sources/MarkdownUI/Views/Blocks/BlockSequence.swift b/Sources/MarkdownUI/Views/Blocks/BlockSequence.swift
index fd56e638..aac0a36a 100644
--- a/Sources/MarkdownUI/Views/Blocks/BlockSequence.swift
+++ b/Sources/MarkdownUI/Views/Blocks/BlockSequence.swift
@@ -26,8 +26,9 @@ where
     VStack(alignment: self.textAlignment.alignment.horizontal, spacing: 0) {
       ForEach(self.data, id: \.self) { element in
         self.content(element.index, element.value)
-          .onPreferenceChange(BlockMarginsPreference.self) { value in
-            self.blockMargins[element.hashValue] = value
+          .onPreferenceChange(BlockMarginsPreference.self) { [marginBinding = $blockMargins[element.hashValue]] value in
+            // Roundabout capture makes closure sendable (see #389)
+            marginBinding.wrappedValue = value
           }
           .padding(.top, self.topPaddingLength(for: element))
       }
diff --git a/Sources/MarkdownUI/Views/Blocks/ColumnWidthPreference.swift b/Sources/MarkdownUI/Views/Blocks/ColumnWidthPreference.swift
index 319c69fd..773adfce 100644
--- a/Sources/MarkdownUI/Views/Blocks/ColumnWidthPreference.swift
+++ b/Sources/MarkdownUI/Views/Blocks/ColumnWidthPreference.swift
@@ -9,7 +9,7 @@ extension View {
     )
   }
 
-  func onColumnWidthChange(perform action: @escaping ([Int: CGFloat]) -> Void) -> some View {
+  func onColumnWidthChange(perform action: @escaping @Sendable ([Int: CGFloat]) -> Void) -> some View {
     self.onPreferenceChange(ColumnWidthPreference.self, perform: action)
   }
 }
diff --git a/Sources/MarkdownUI/Views/Blocks/NumberedListView.swift b/Sources/MarkdownUI/Views/Blocks/NumberedListView.swift
index fb3098ef..0da685fd 100644
--- a/Sources/MarkdownUI/Views/Blocks/NumberedListView.swift
+++ b/Sources/MarkdownUI/Views/Blocks/NumberedListView.swift
@@ -41,8 +41,9 @@ struct NumberedListView: View {
     )
     .environment(\.listLevel, self.listLevel + 1)
     .environment(\.tightSpacingEnabled, self.isTight)
-    .onColumnWidthChange { columnWidths in
-      self.markerWidth = columnWidths[0]
+    .onColumnWidthChange { [$markerWidth] columnWidths in
+      // Roundabout capture makes closure sendable (see #389)
+      $markerWidth.wrappedValue = columnWidths[0]
     }
   }
 }