diff --git a/mpy-cross/mpconfigport.h b/mpy-cross/mpconfigport.h
index 95922d04ff..9d455c0af1 100644
--- a/mpy-cross/mpconfigport.h
+++ b/mpy-cross/mpconfigport.h
@@ -135,6 +135,7 @@ typedef long mp_off_t;
 #define MP_ENDIANNESS_LITTLE        (1)
 #define NORETURN                    __declspec(noreturn)
 #define MP_NOINLINE                 __declspec(noinline)
+#define MP_ALWAYSINLINE             __forceinline
 #define MP_LIKELY(x)                (x)
 #define MP_UNLIKELY(x)              (x)
 #define MICROPY_PORT_CONSTANTS      { MP_ROM_QSTR(MP_QSTR_dummy), MP_ROM_PTR(NULL) }
diff --git a/ports/windows/mpconfigport.h b/ports/windows/mpconfigport.h
index 39f8c0059c..71814e2147 100644
--- a/ports/windows/mpconfigport.h
+++ b/ports/windows/mpconfigport.h
@@ -256,6 +256,7 @@ typedef long mp_off_t;
 #define NORETURN                    __declspec(noreturn)
 #define MP_WEAK
 #define MP_NOINLINE                 __declspec(noinline)
+#define MP_ALWAYSINLINE             __forceinline
 #define MP_LIKELY(x)                (x)
 #define MP_UNLIKELY(x)              (x)
 #define MICROPY_PORT_CONSTANTS      { MP_ROM_QSTR(MP_QSTR_dummy), MP_ROM_PTR(NULL) } // can't have zero-sized array