diff --git a/include/nlohmann/detail/macro_scope.hpp b/include/nlohmann/detail/macro_scope.hpp
index 770de0b86..214d91cff 100644
--- a/include/nlohmann/detail/macro_scope.hpp
+++ b/include/nlohmann/detail/macro_scope.hpp
@@ -134,7 +134,7 @@
 #endif
 
 #ifndef JSON_HAS_STATIC_RTTI
-    #if defined(_HAS_STATIC_RTTI) && _HAS_STATIC_RTTI != 0
+    #if !defined(_HAS_STATIC_RTTI) || _HAS_STATIC_RTTI != 0
         #define JSON_HAS_STATIC_RTTI 1
     #else
         #define JSON_HAS_STATIC_RTTI 0
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 9ba1595ae..669c724f0 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -2486,7 +2486,7 @@ JSON_HEDLEY_DIAGNOSTIC_POP
 #endif
 
 #ifndef JSON_HAS_STATIC_RTTI
-    #if defined(_HAS_STATIC_RTTI) && _HAS_STATIC_RTTI != 0
+    #if !defined(_HAS_STATIC_RTTI) || _HAS_STATIC_RTTI != 0
         #define JSON_HAS_STATIC_RTTI 1
     #else
         #define JSON_HAS_STATIC_RTTI 0