diff --git a/Sources/MacroTesting/AssertMacro.swift b/Sources/MacroTesting/AssertMacro.swift
index 5de675a..0d4d105 100644
--- a/Sources/MacroTesting/AssertMacro.swift
+++ b/Sources/MacroTesting/AssertMacro.swift
@@ -767,7 +767,7 @@ internal func macroName(className: String, isExpression: Bool) -> String {
   return name
 }
 
-struct MacroTestingConfiguration {
+struct MacroTestingConfiguration: Sendable {
   @TaskLocal static var current = Self()
 
   var indentationWidth: Trivia? = nil