diff --git a/NumLib/NewtonRaphson.h b/NumLib/NewtonRaphson.h
index f3c86a44b2cb3d8e03189d340803720f15fe8d04..4ef3f0473af00c300809d5502ce4e9693e5a4e88 100644
--- a/NumLib/NewtonRaphson.h
+++ b/NumLib/NewtonRaphson.h
@@ -17,7 +17,6 @@
 
 namespace NumLib
 {
-
 struct NewtonRaphsonSolverParameters
 {
     int maximum_iterations;
@@ -101,7 +100,7 @@ public:
                 "residual: "
                 "{:g}",
                 iteration - 1, increment.norm(), residual.norm());
-            return {};
+            return std::nullopt;
         }
 
         return iteration;