diff --git a/include/aidge/operator/Operator.hpp b/include/aidge/operator/Operator.hpp
index a145aab061c714ada80728e5b6bb84ad66605e52..edaeaf42c15d52669cfe7b6c178277934351a385 100644
--- a/include/aidge/operator/Operator.hpp
+++ b/include/aidge/operator/Operator.hpp
@@ -67,8 +67,16 @@ enum class InputCategory : unsigned int {
     OptionalParam = (1 << 2) | Optional, /**< Optional parameter input. */
     All = static_cast<unsigned int>(-1)
 };
+
+
+#ifdef _MSC_VER
+template <>
+constexpr bool enable_bitmask_operators<InputCategory> = true;
+#else
 template <>
 inline constexpr bool enable_bitmask_operators<InputCategory> = true;
+#endif
+
 
 /**
  * @class Operator