diff --git a/include/ctbignum/config.hpp b/include/ctbignum/config.hpp
new file mode 100644
index 0000000..b8326df
--- /dev/null
+++ b/include/ctbignum/config.hpp
@@ -0,0 +1,27 @@
+//
+//   This file is part of:
+//
+//   CTBignum 
+//
+//   C++ Library for Compile-Time and Run-Time Multi-Precision and Modular Arithmetic
+//   
+//   Copyright 2018 Authors
+//
+//   Licensed under the Apache License, Version 2.0 (the "License");
+//   you may not use this file except in compliance with the License.
+//   You may obtain a copy of the License at
+//
+//       http://www.apache.org/licenses/LICENSE-2.0
+//
+//   Unless required by applicable law or agreed to in writing, software
+//   distributed under the License is distributed on an "AS IS" BASIS,
+//   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//   See the License for the specific language governing permissions and
+//   limitations under the License.
+//
+#ifndef CT_CONFIG_HPP
+#define CT_CONFIG_HPP
+
+#define CBN_ALWAYS_INLINE [[gnu::always_inline]
+
+#endif
diff --git a/include/ctbignum/montgomery.hpp b/include/ctbignum/montgomery.hpp
index 14ca321..0f41191 100644
--- a/include/ctbignum/montgomery.hpp
+++ b/include/ctbignum/montgomery.hpp
@@ -24,13 +24,15 @@
 #ifndef CT_MONTGOMERY_HPP
 #define CT_MONTGOMERY_HPP
 
-#include <cstddef> // std::size_t
 #include <ctbignum/addition.hpp>
+#include <ctbignum/config.hpp>
 #include <ctbignum/gcd.hpp>
 #include <ctbignum/mult.hpp>
 #include <ctbignum/relational_ops.hpp>
 #include <ctbignum/slicing.hpp>
 #include <ctbignum/type_traits.hpp>
+
+#include <cstddef> // std::size_t
 #include <limits>
 
 namespace cbn {
@@ -79,7 +81,7 @@ constexpr auto montgomery_reduction(big_int<N1, T> A,
 
 
 template <typename T, std::size_t N, T... Modulus>
-[[gnu::always_inline]]
+CBN_ALWAYS_INLINE
 constexpr auto montgomery_mul(big_int<N, T> x, big_int<N, T> y,
                               std::integer_sequence<T, Modulus...>) {
   // Montgomery multiplication with compile-time modulus
diff --git a/include/ctbignum/mult.hpp b/include/ctbignum/mult.hpp
index 56638f5..a378d55 100644
--- a/include/ctbignum/mult.hpp
+++ b/include/ctbignum/mult.hpp
@@ -25,6 +25,7 @@
 #define CT_MULT_HPP
 
 #include <ctbignum/bigint.hpp>
+#include <ctbignum/config.hpp>
 #include <ctbignum/type_traits.hpp>
 
 #include <algorithm>
@@ -50,7 +51,7 @@ constexpr auto short_mul(big_int<N, T> a, T b) {
 }
 
 template <size_t padding_limbs = 0, size_t M, size_t N, typename T>
-[[gnu::always_inline]]
+CBN_ALWAYS_INLINE 
 constexpr auto mul(big_int<M, T> u, big_int<N, T> v) {
 
   using TT = typename dbl_bitlen<T>::type;