diff --git a/core/OS.hpp b/core/OS.hpp
index cf5a090eb..93e2804e4 100644
--- a/core/OS.hpp
+++ b/core/OS.hpp
@@ -107,6 +107,7 @@
 #include <xmmintrin.h>
 #include <emmintrin.h>
 #include <immintrin.h>
+#include <mmintrin.h>
 #endif
 
 #if defined(ZT_ARCH_X64) || defined(i386) || defined(__i386) || defined(__i386__) || defined(__i486__) || defined(__i586__) || defined(__i686__) || defined(_M_IX86) || defined(__X86__) || defined(_X86_) || defined(__I86__) || defined(__INTEL__) || defined(__386)