diff --git a/mdbx.h++ b/mdbx.h++
index 5ae3838a..7ae347c4 100644
--- a/mdbx.h++
+++ b/mdbx.h++
@@ -791,9 +791,7 @@ struct LIBMDBX_API_TYPE slice : public ::MDBX_val {
 
   /// \brief Build an invalid slice which non-zero length and refers to null
   /// address.
-  MDBX_CXX11_CONSTEXPR static slice invalid() noexcept {
-    return slice(size_t(-1));
-  }
+  inline static slice invalid() noexcept { return slice(size_t(-1)); }
 
 protected:
   MDBX_CXX11_CONSTEXPR slice(size_t invalid_length) noexcept