diff --git a/src/libslic3r/Fill/FillBase.hpp b/src/libslic3r/Fill/FillBase.hpp
index 0fee1fe56..ab150c48c 100644
--- a/src/libslic3r/Fill/FillBase.hpp
+++ b/src/libslic3r/Fill/FillBase.hpp
@@ -88,9 +88,9 @@ public:
     // Index of the layer.
     size_t      layer_id;
     // Z coordinate of the top print surface, in unscaled coordinates
-    coordf_t    z;
+    double      z;
     // infill / perimeter overlap, in unscaled coordinates 
-    coordf_t    overlap;
+    double      overlap;
     ExPolygons  no_overlap_expolygons;
     // in radians, ccw, 0 = East
     float       angle;
diff --git a/src/libslic3r/Fill/FillSmooth.cpp b/src/libslic3r/Fill/FillSmooth.cpp
index 561c6a0f6..4f6276ee6 100644
--- a/src/libslic3r/Fill/FillSmooth.cpp
+++ b/src/libslic3r/Fill/FillSmooth.cpp
@@ -46,7 +46,10 @@ namespace Slic3r {
         }
         else{
             Surface surfaceNoOverlap(srf_source);
-            for (const ExPolygon &poly : this->no_overlap_expolygons) {
+            //use half overlap instead of none.
+            ExPolygons half_overlap = offset_ex(this->no_overlap_expolygons, scale_(this->overlap / 2));
+            half_overlap = intersection_ex({ srf_source.expolygon }, half_overlap);
+            for (const ExPolygon &poly : half_overlap) {
                 if (poly.empty()) continue;
                 surfaceNoOverlap.expolygon = poly;
                 this->fill_expolygon(idx, *eec, surfaceNoOverlap, params_modifided, volume);
diff --git a/src/libslic3r/Fill/FillSmooth.hpp b/src/libslic3r/Fill/FillSmooth.hpp
index fa7a0b4b6..1c8a8fae7 100644
--- a/src/libslic3r/Fill/FillSmooth.hpp
+++ b/src/libslic3r/Fill/FillSmooth.hpp
@@ -15,7 +15,7 @@ public:
         anglePass[0] = 0;
         anglePass[1] = float(M_PI/2);
         anglePass[2] = 0;
-        fillPattern[0] = InfillPattern::ipRectilinearWGapFill;
+        fillPattern[0] = InfillPattern::ipMonotonicWGapFill;//ipRectilinearWGapFill;
         fillPattern[1] = InfillPattern::ipRectilinear;
         fillPattern[2] = InfillPattern::ipRectilinear;
         rolePass[0] = erNone;// erTopSolidInfill;