diff --git a/MathLib/LinAlg/Eigen/EigenOption.h b/MathLib/LinAlg/Eigen/EigenOption.h
index e38927baecb65219ea00348398c1249a69418536..720afeee7ef513d3bb9ad9a7004cdca0f74f1592 100644
--- a/MathLib/LinAlg/Eigen/EigenOption.h
+++ b/MathLib/LinAlg/Eigen/EigenOption.h
@@ -39,7 +39,7 @@ struct EigenOption final
     /// Preconditioner type
     PreconType precon_type;
     /// Maximum iteration count
-    std::size_t max_iterations;
+    int max_iterations;
     /// Error tolerance
     double error_tolerance;