diff --git a/packages/thyra/core/src/interfaces/operator_solve/fundamental/Thyra_LinearOpWithSolveBase_decl.hpp b/packages/thyra/core/src/interfaces/operator_solve/fundamental/Thyra_LinearOpWithSolveBase_decl.hpp
index ffd7e8b542e9..6049e827bb02 100644
--- a/packages/thyra/core/src/interfaces/operator_solve/fundamental/Thyra_LinearOpWithSolveBase_decl.hpp
+++ b/packages/thyra/core/src/interfaces/operator_solve/fundamental/Thyra_LinearOpWithSolveBase_decl.hpp
@@ -279,6 +279,8 @@ class LinearOpWithSolveBase
 {
 public:
 
+  using scalar_type = Scalar;
+
   /** \name Public interface funtions. */
   //@{