diff --git a/GeoLib/Polyline.cpp b/GeoLib/Polyline.cpp
index 3522fa12dc814d2835fb6b7c8d12da5c8def0cb5..0c21c3cc374cf133d6899eadac6a0d4535281e04 100644
--- a/GeoLib/Polyline.cpp
+++ b/GeoLib/Polyline.cpp
@@ -524,12 +524,12 @@ LineSegment Polyline::SegmentIterator::operator*()
     return _polyline->getSegment(_segment_number);
 }
 
-bool Polyline::SegmentIterator::operator==(SegmentIterator const& other)
+bool Polyline::SegmentIterator::operator==(SegmentIterator const& other) const
 {
     return !(*this != other);
 }
 
-bool Polyline::SegmentIterator::operator!=(SegmentIterator const& other)
+bool Polyline::SegmentIterator::operator!=(SegmentIterator const& other) const
 {
     return other._segment_number != _segment_number ||
            other._polyline != _polyline;
diff --git a/GeoLib/Polyline.h b/GeoLib/Polyline.h
index f043f1f67ed4768208f1e18c6c223b439df46c9d..13dbd0e72ddf33b661a5b5add68bab87f6d64b22 100644
--- a/GeoLib/Polyline.h
+++ b/GeoLib/Polyline.h
@@ -72,9 +72,9 @@ public:
 
         LineSegment operator*();
 
-        bool operator==(SegmentIterator const& other);
+        bool operator==(SegmentIterator const& other) const;
 
-        bool operator!=(SegmentIterator const& other);
+        bool operator!=(SegmentIterator const& other) const;
 
         SegmentIterator& operator+=(std::vector<GeoLib::Point>::difference_type n);
 
diff --git a/ParameterLib/FunctionParameter.h b/ParameterLib/FunctionParameter.h
index 8a316c5f1fe741e08ce885cbbf44b0be288137d0..2dbb884c894e78f6a35e677e53bcfee8710850d2 100644
--- a/ParameterLib/FunctionParameter.h
+++ b/ParameterLib/FunctionParameter.h
@@ -10,11 +10,11 @@
 
 #pragma once
 
+#include <exprtk.hpp>
 #include <utility>
 #include <vector>
 
-#include <exprtk.hpp>
-
+#include "MathLib/InterpolationAlgorithms/PiecewiseLinearInterpolation.h"
 #include "Parameter.h"
 #include "Utils.h"
 
@@ -147,6 +147,10 @@ private:
 };
 
 std::unique_ptr<ParameterBase> createFunctionParameter(
-    std::string const& name, BaseLib::ConfigTree const& config);
+    std::string const& name,
+    BaseLib::ConfigTree const& config,
+    std::map<std::string,
+             std::unique_ptr<MathLib::PiecewiseLinearInterpolation>> const&
+        curves);
 
 }  // namespace ParameterLib