diff --git a/include/nlohmann/detail/macro_scope.hpp b/include/nlohmann/detail/macro_scope.hpp
index 400530a60a..76a0dc62cf 100644
--- a/include/nlohmann/detail/macro_scope.hpp
+++ b/include/nlohmann/detail/macro_scope.hpp
@@ -301,3 +301,7 @@
 #else
     #define JSON_EXPLICIT explicit
 #endif
+
+#ifndef JSON_DIAGNOSTICS
+    #define JSON_DIAGNOSTICS 0
+#endif