diff --git a/include/spdlog/mdc.h b/include/spdlog/mdc.h
index c70da856..6c4c527f 100644
--- a/include/spdlog/mdc.h
+++ b/include/spdlog/mdc.h
@@ -1,3 +1,5 @@
+#pragma once
+
 #include <spdlog/common.h>
 #include <map>
 
@@ -28,4 +30,4 @@ public:
     }
 };
 
-}  // namespace spdlog
\ No newline at end of file
+}  // namespace spdlog