diff --git a/ProcessLib/Parameter/ConstantParameter.h b/ProcessLib/Parameter/ConstantParameter.h
index 0e72b8f4a6cc304a1f9299191b51dc8039d90dd0..3256d0cc3976bd805794211acb48b2894e0f3046 100644
--- a/ProcessLib/Parameter/ConstantParameter.h
+++ b/ProcessLib/Parameter/ConstantParameter.h
@@ -31,7 +31,7 @@ struct ConstantParameter final : public Parameter<T>
         return static_cast<unsigned>(_value.size());
     }
 
-    std::vector<T> const& getTuple(
+    std::vector<T> const& operator()(
         double const /*t*/, SpatialPosition const& /*pos*/) const override
     {
         return _value;
diff --git a/ProcessLib/Parameter/MeshElementParameter.h b/ProcessLib/Parameter/MeshElementParameter.h
index 298065a64c7a8cf3599b64c7b3d787a821d7007a..eda4c4fbaa1f4f7daa12f61bec4928e3103174a9 100644
--- a/ProcessLib/Parameter/MeshElementParameter.h
+++ b/ProcessLib/Parameter/MeshElementParameter.h
@@ -34,8 +34,8 @@ struct MeshElementParameter final : public Parameter<T> {
         return _property.getNumberOfComponents();
     }
 
-    std::vector<T> const& getTuple(double const /*t*/,
-                                   SpatialPosition const& pos) const override
+    std::vector<T> const& operator()(double const /*t*/,
+                                     SpatialPosition const& pos) const override
     {
         auto const e = pos.getElementID();
         assert(e);
diff --git a/ProcessLib/Parameter/MeshNodeParameter.h b/ProcessLib/Parameter/MeshNodeParameter.h
index 2ebecc428de4e0c1d82f7c87ee48e2b60714477e..35f9041e0639cd62f526e2c7fa7a7c541f5dda04 100644
--- a/ProcessLib/Parameter/MeshNodeParameter.h
+++ b/ProcessLib/Parameter/MeshNodeParameter.h
@@ -34,8 +34,8 @@ struct MeshNodeParameter final : public Parameter<T> {
         return _property.getNumberOfComponents();
     }
 
-    std::vector<T> const& getTuple(double const /*t*/,
-                                   SpatialPosition const& pos) const override
+    std::vector<T> const& operator()(double const /*t*/,
+                                     SpatialPosition const& pos) const override
     {
         auto const n = pos.getNodeID();
         assert(n);
diff --git a/ProcessLib/Parameter/Parameter.h b/ProcessLib/Parameter/Parameter.h
index aec56e55794968995d12eed688988bfd4c284aee..1ba14f23f5269591c846893cd98f6da8b9735d22 100644
--- a/ProcessLib/Parameter/Parameter.h
+++ b/ProcessLib/Parameter/Parameter.h
@@ -52,7 +52,7 @@ struct Parameter : public ParameterBase
     virtual unsigned getNumberOfComponents() const = 0;
 
     //! Returns the parameter value at the given time and position.
-    virtual std::vector<T> const& getTuple(
+    virtual std::vector<T> const& operator()(
         double const t, SpatialPosition const& pos) const = 0;
 };