diff --git a/DiagnosticsTests/DiagnosticsReporterTests.swift b/DiagnosticsTests/DiagnosticsReporterTests.swift
index 4828d9f..aac76d7 100644
--- a/DiagnosticsTests/DiagnosticsReporterTests.swift
+++ b/DiagnosticsTests/DiagnosticsReporterTests.swift
@@ -89,7 +89,7 @@ final class DiagnosticsReporterTests: XCTestCase {
 }
 
 struct MockedReport: DiagnosticsReporting {
-    var diagnostics: Diagnostics = [:]
+    var diagnostics: Diagnostics = [String: String]()
     func report() -> DiagnosticsChapter {
         return DiagnosticsChapter(title: UUID().uuidString, diagnostics: diagnostics)
     }
diff --git a/Sources/DiagnosticsChapter.swift b/Sources/DiagnosticsChapter.swift
index bc37d0e..640c995 100644
--- a/Sources/DiagnosticsChapter.swift
+++ b/Sources/DiagnosticsChapter.swift
@@ -9,7 +9,7 @@
 import Foundation
 
 /// Defines a Diagnostics Chapter which will end up in the report as HTML.
-public struct DiagnosticsChapter {
+public struct DiagnosticsChapter: Sendable {
 
     /// The title of the diagnostics report which will also be used as HTML anchor.
     public let title: String
diff --git a/Sources/DiagnosticsReport.swift b/Sources/DiagnosticsReport.swift
index 09b3f53..6e4df25 100644
--- a/Sources/DiagnosticsReport.swift
+++ b/Sources/DiagnosticsReport.swift
@@ -13,8 +13,8 @@ import AppKit
 #endif
 
 /// The actual diagnostics report containing the compiled data of all reporters.
-public struct DiagnosticsReport {
-    public enum MimeType: String {
+public struct DiagnosticsReport: Sendable {
+    public enum MimeType: String, Sendable {
         case html = "text/html"
     }
 
diff --git a/Sources/HTMLGenerating.swift b/Sources/HTMLGenerating.swift
index 55a7238..26fc9ae 100644
--- a/Sources/HTMLGenerating.swift
+++ b/Sources/HTMLGenerating.swift
@@ -10,7 +10,7 @@ import Foundation
 
 public typealias HTML = String
 
-public protocol HTMLGenerating {
+public protocol HTMLGenerating: Sendable {
     func html() -> HTML
 }
 
diff --git a/Sources/Reporters/DirectoryTree/DirectoryTreeNode.swift b/Sources/Reporters/DirectoryTree/DirectoryTreeNode.swift
index 75cae1c..5d9005b 100644
--- a/Sources/Reporters/DirectoryTree/DirectoryTreeNode.swift
+++ b/Sources/Reporters/DirectoryTree/DirectoryTreeNode.swift
@@ -8,7 +8,7 @@
 import Foundation
 
 /// A file system node with it's path, name and contents.
-indirect enum DirectoryTreeNode {
+indirect enum DirectoryTreeNode: Sendable {
     /// A regular file.
     case file(String, String)