diff --git a/include/spdlog/details/backtracer.h b/include/spdlog/details/backtracer.h
index b7476bc9..f5892c0a 100644
--- a/include/spdlog/details/backtracer.h
+++ b/include/spdlog/details/backtracer.h
@@ -17,7 +17,7 @@ namespace spdlog {
 namespace details {
 class SPDLOG_API backtracer
 {
-    mutable std::mutex mutex_;
+    std::mutex mutex_;
     std::atomic<bool> enabled_{false};
     circular_q<log_msg_buffer> messages_;