diff --git a/src/catch2/internal/catch_xmlwriter.hpp b/src/catch2/internal/catch_xmlwriter.hpp
index 41914e15..5be8277d 100644
--- a/src/catch2/internal/catch_xmlwriter.hpp
+++ b/src/catch2/internal/catch_xmlwriter.hpp
@@ -77,7 +77,7 @@ namespace Catch {
             }
 
         private:
-            mutable XmlWriter* m_writer = nullptr;
+            XmlWriter* m_writer = nullptr;
             XmlFormatting m_fmt;
         };