diff --git a/include/spdlog/sinks/ansicolor_sink.h b/include/spdlog/sinks/ansicolor_sink.h
index 905d270a..3fbbf27b 100644
--- a/include/spdlog/sinks/ansicolor_sink.h
+++ b/include/spdlog/sinks/ansicolor_sink.h
@@ -135,6 +135,7 @@ public:
 
     bool should_color()
     {
+        std::lock_guard<mutex_t> lock(mutex_);
         return should_do_colors_;
     }