Improve constness of level2 blas API.
diff --git a/lapack/lapack_common.h b/lapack/lapack_common.h
index a935987..c872a81 100644
--- a/lapack/lapack_common.h
+++ b/lapack/lapack_common.h
@@ -11,6 +11,7 @@
 #define EIGEN_LAPACK_COMMON_H
 
 #include "../blas/common.h"
+#include "../Eigen/src/misc/lapack.h"
 
 #define EIGEN_LAPACK_FUNC(FUNC,ARGLIST)               \
   extern "C" { int EIGEN_BLAS_FUNC(FUNC) ARGLIST; }   \