diff --git a/xs/src/libslic3r/Fill/FillGyroid.cpp b/xs/src/libslic3r/Fill/FillGyroid.cpp
index 002a4752b..5fb16ba4d 100644
--- a/xs/src/libslic3r/Fill/FillGyroid.cpp
+++ b/xs/src/libslic3r/Fill/FillGyroid.cpp
@@ -57,7 +57,7 @@ Polyline FillGyroid::makeLineHori(double xPos, double yPos, double width, double
     return polyline;
 }
 
-inline void FillGyroid::correctOrderAndAdd(const int num, Polyline &poly, Polylines &array){
+inline void FillGyroid::correctOrderAndAdd(const int num, Polyline poly, Polylines &array){
     if(num%2==0){
         Points temp(poly.points.rbegin(), poly.points.rend());
         poly.points.assign(temp.begin(),temp.end());
diff --git a/xs/src/libslic3r/Fill/FillGyroid.hpp b/xs/src/libslic3r/Fill/FillGyroid.hpp
index 8c52e1347..4467a88de 100644
--- a/xs/src/libslic3r/Fill/FillGyroid.hpp
+++ b/xs/src/libslic3r/Fill/FillGyroid.hpp
@@ -36,7 +36,7 @@ protected:
     // create the gyroid grid to clip.
     Polylines makeGrid(coord_t gridZ, double density, double layer_width, size_t gridWidth, size_t gridHeight, size_t curveType);
     //add line poly in reverse if needed into array
-    inline void correctOrderAndAdd(const int num, Polyline &poly, Polylines &array);
+    inline void correctOrderAndAdd(const int num, Polyline poly, Polylines &array);
     //create a curved horinzontal line  (for each x, compute y)
     Polyline makeLineHori(double xPos, double yPos, double width, double height, 
         double currentYBegin, double segmentSize, coord_t scaleFactor, 
@@ -52,4 +52,4 @@ protected:
 
 } // namespace Slic3r
 
-#endif // slic3r_FillGyroid_hpp_
\ No newline at end of file
+#endif // slic3r_FillGyroid_hpp_