diff --git a/src/libslic3r/Fill/FillRectilinear.cpp b/src/libslic3r/Fill/FillRectilinear.cpp
index e27017b..2389f72 100644
--- a/src/libslic3r/Fill/FillRectilinear.cpp
+++ b/src/libslic3r/Fill/FillRectilinear.cpp
@@ -2993,6 +2993,10 @@ Polylines FillGrid::fill_surface(const Surface *surface, const FillParams &param
             { { 0.f, 0.f }, { float(M_PI / 2.), 0.f } },
             polylines_out))
         BOOST_LOG_TRIVIAL(error) << "FillGrid::fill_surface() failed to fill a region.";
+    //w18 reverse fill path
+    if (this->layer_id % 2 == 1)
+        for (int i = 0; i < polylines_out.size(); i++)
+            std::reverse(polylines_out[i].begin(), polylines_out[i].end());
     return polylines_out;
 }