diff --git a/src/math_eigen_impl.h b/src/math_eigen_impl.h
index 80502b1701..7d6f0385ae 100644
--- a/src/math_eigen_impl.h
+++ b/src/math_eigen_impl.h
@@ -935,7 +935,7 @@ run(real_t<T>& eigvalue, std::vector<T>& eigvec) const
   //assert(matrix_size > 0);
   //assert(0 < this->tridiag_eps_ratio && this->tridiag_eps_ratio < 1);
 
-  std::vector<std::vector<T>> u;     // Lanczos vectors
+  std::vector<std::vector<T>> u; // Lanczos vectors
   std::vector<real_t<T>> alpha; // Diagonal elements of an approximated tridiagonal matrix
   std::vector<real_t<T>> beta;  // Subdiagonal elements of an approximated tridiagonal matrix