diff --git a/src/msm_avx.cpp b/src/msm_avx.cpp
index ae03f2c9..8634f276 100644
--- a/src/msm_avx.cpp
+++ b/src/msm_avx.cpp
@@ -15,6 +15,7 @@
 #define XBYAK_NO_EXCEPTION
 #include "xbyak/xbyak_util.h"
 
+namespace {
 typedef mcl::Unit Unit;
 typedef __m512i Vec;
 typedef __mmask8 Vmask;
@@ -1312,6 +1313,8 @@ void mulVec_naive(mcl::msm::G1A& P, const mcl::msm::G1A *x, const mcl::msm::FrA
 }
 #endif
 
+}
+
 namespace mcl { namespace msm {
 
 void mulVecAVX512(Unit *_P, Unit *_x, const Unit *_y, size_t n)