diff --git a/Eigen/Core b/Eigen/Core
index 2c376ba3a..6c79bcfae 100644
--- a/Eigen/Core
+++ b/Eigen/Core
@@ -156,6 +156,7 @@
       #if EIGEN_COMP_ICC >= 1110
         #include <immintrin.h>
       #else
+        #include <mmintrin.h>
         #include <emmintrin.h>
         #include <xmmintrin.h>
         #ifdef  EIGEN_VECTORIZE_SSE3