diff --git a/include/nameof.hpp b/include/nameof.hpp
index 1dc08e5..78462f2 100644
--- a/include/nameof.hpp
+++ b/include/nameof.hpp
@@ -45,11 +45,13 @@
 
 // Checks nameof_type compiler compatibility.
 #if defined(__clang__) || defined(__GNUC__) || defined(_MSC_VER)
+#  undef NAMEOF_TYPE_SUPPORTED
 #  define NAMEOF_TYPE_SUPPORTED 1
 #endif
 
 // Checks nameof_enum compiler compatibility.
 #if defined(__clang__) || defined(__GNUC__) && __GNUC__>= 9 || defined(_MSC_VER)
+#  undef NAMEOF_ENUM_SUPPORTED
 #  define NAMEOF_ENUM_SUPPORTED 1
 #endif