diff --git a/mdbx.h++ b/mdbx.h++
index 5dc57b52..e8614e41 100644
--- a/mdbx.h++
+++ b/mdbx.h++
@@ -162,6 +162,20 @@
 #define MDBX_CXX20_CONSTEXPR inline
 #endif /* MDBX_CXX20_CONSTEXPR */
 
+#if CONSTEXPR_ENUM_FLAGS_OPERATIONS || defined(DOXYGEN)
+#define MDBX_CXX01_CONSTEXPR_ENUM MDBX_CXX01_CONSTEXPR
+#define MDBX_CXX11_CONSTEXPR_ENUM MDBX_CXX11_CONSTEXPR
+#define MDBX_CXX14_CONSTEXPR_ENUM MDBX_CXX14_CONSTEXPR
+#define MDBX_CXX17_CONSTEXPR_ENUM MDBX_CXX17_CONSTEXPR
+#define MDBX_CXX20_CONSTEXPR_ENUM MDBX_CXX20_CONSTEXPR
+#else
+#define MDBX_CXX01_CONSTEXPR_ENUM inline
+#define MDBX_CXX11_CONSTEXPR_ENUM inline
+#define MDBX_CXX14_CONSTEXPR_ENUM inline
+#define MDBX_CXX17_CONSTEXPR_ENUM inline
+#define MDBX_CXX20_CONSTEXPR_ENUM inline
+#endif /* CONSTEXPR_ENUM_FLAGS_OPERATIONS */
+
 /** Workaround for old compilers without support assertion inside `constexpr`
  * functions. */
 #if defined(CONSTEXPR_ASSERT)
@@ -3198,18 +3212,8 @@ struct LIBMDBX_API_TYPE map_handle {
                               map_handle::state state) noexcept;
     info(const info &) noexcept = default;
     info &operator=(const info &) noexcept = default;
-#if CONSTEXPR_ENUM_FLAGS_OPERATIONS
-    MDBX_CXX11_CONSTEXPR
-#else
-    inline
-#endif
-    ::mdbx::key_mode key_mode() const noexcept;
-#if CONSTEXPR_ENUM_FLAGS_OPERATIONS
-    MDBX_CXX11_CONSTEXPR
-#else
-    inline
-#endif
-    ::mdbx::value_mode value_mode() const noexcept;
+    MDBX_CXX11_CONSTEXPR_ENUM mdbx::key_mode key_mode() const noexcept;
+    MDBX_CXX11_CONSTEXPR_ENUM mdbx::value_mode value_mode() const noexcept;
   };
 };
 
@@ -5491,17 +5495,13 @@ MDBX_CXX11_CONSTEXPR map_handle::info::info(map_handle::flags flags,
                                             map_handle::state state) noexcept
     : flags(flags), state(state) {}
 
-#if CONSTEXPR_ENUM_FLAGS_OPERATIONS
-MDBX_CXX11_CONSTEXPR
-#endif
-::mdbx::key_mode map_handle::info::key_mode() const noexcept {
+MDBX_CXX11_CONSTEXPR_ENUM mdbx::key_mode
+map_handle::info::key_mode() const noexcept {
   return ::mdbx::key_mode(flags & (MDBX_REVERSEKEY | MDBX_INTEGERKEY));
 }
 
-#if CONSTEXPR_ENUM_FLAGS_OPERATIONS
-MDBX_CXX11_CONSTEXPR
-#endif
-::mdbx::value_mode map_handle::info::value_mode() const noexcept {
+MDBX_CXX11_CONSTEXPR_ENUM mdbx::value_mode
+map_handle::info::value_mode() const noexcept {
   return ::mdbx::value_mode(flags & (MDBX_DUPSORT | MDBX_REVERSEDUP |
                                      MDBX_DUPFIXED | MDBX_INTEGERDUP));
 }