diff --git a/lib/Grid_Eigen_Dense.h b/lib/Grid_Eigen_Dense.h
index 3e5ca1d1..9445c76c 100644
--- a/lib/Grid_Eigen_Dense.h
+++ b/lib/Grid_Eigen_Dense.h
@@ -1,4 +1,5 @@
 #pragma once
+#define EIGEN_USE_MKL_ALL
 #if defined __GNUC__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"