diff --git a/src/libslic3r/Arachne/utils/ExtrusionLine.cpp b/src/libslic3r/Arachne/utils/ExtrusionLine.cpp
index c594b8b91e..4ddbb01d1c 100644
--- a/src/libslic3r/Arachne/utils/ExtrusionLine.cpp
+++ b/src/libslic3r/Arachne/utils/ExtrusionLine.cpp
@@ -268,13 +268,13 @@ void extrusion_paths_append(ExtrusionPaths &dst, const ClipperLib_Z::Paths &extr
 {
     for (const ClipperLib_Z::Path &extrusion_path : extrusion_paths) {
         ThickPolyline thick_polyline = Arachne::to_thick_polyline(extrusion_path);
-        Slic3r::append(dst, thick_polyline_to_extrusion_paths(thick_polyline, role, flow, scaled<float>(0.05), 0));
+        Slic3r::append(dst, thick_polyline_to_extrusion_paths(thick_polyline, role, flow, scaled<float>(0.05), SCALED_EPSILON));
     }
 }
 
 void extrusion_paths_append(ExtrusionPaths &dst, const Arachne::ExtrusionLine &extrusion, const ExtrusionRole role, const Flow &flow)
 {
     ThickPolyline thick_polyline = Arachne::to_thick_polyline(extrusion);
-    Slic3r::append(dst, thick_polyline_to_extrusion_paths(thick_polyline, role, flow, scaled<float>(0.05), 0));
+    Slic3r::append(dst, thick_polyline_to_extrusion_paths(thick_polyline, role, flow, scaled<float>(0.05), SCALED_EPSILON));
 }
 } // namespace Slic3r
\ No newline at end of file
diff --git a/src/libslic3r/PerimeterGenerator.cpp b/src/libslic3r/PerimeterGenerator.cpp
index 539679e8d4..0bbe601e20 100644
--- a/src/libslic3r/PerimeterGenerator.cpp
+++ b/src/libslic3r/PerimeterGenerator.cpp
@@ -25,7 +25,7 @@ ExtrusionPaths thick_polyline_to_extrusion_paths(const ThickPolyline &thick_poly
 
         const coordf_t line_len = line.length();
         if (line_len < SCALED_EPSILON) continue;
-        
+
         double thickness_delta = fabs(line.a_width - line.b_width);
         if (thickness_delta > tolerance) {
             const auto segments = (unsigned int)ceil(thickness_delta / tolerance);
@@ -37,18 +37,18 @@ ExtrusionPaths thick_polyline_to_extrusion_paths(const ThickPolyline &thick_poly
                 width.push_back(line.a_width);
                 for (size_t j = 1; j < segments; ++j) {
                     pp.push_back((line.a.cast<double>() + (line.b - line.a).cast<double>().normalized() * (j * seg_len)).cast<coord_t>());
-                    
+
                     coordf_t w = line.a_width + (j*seg_len) * (line.b_width-line.a_width) / line_len;
                     width.push_back(w);
                     width.push_back(w);
                 }
                 pp.push_back(line.b);
                 width.push_back(line.b_width);
-                
+
                 assert(pp.size() == segments + 1u);
                 assert(width.size() == segments*2);
             }
-            
+
             // delete this line and insert new ones
             lines.erase(lines.begin() + i);
             for (size_t j = 0; j < segments; ++j) {
@@ -57,18 +57,18 @@ ExtrusionPaths thick_polyline_to_extrusion_paths(const ThickPolyline &thick_poly
                 new_line.b_width = width[2*j+1];
                 lines.insert(lines.begin() + i + j, new_line);
             }
-            
+
             -- i;
             continue;
         }
-        
-        const double w = fmax(line.a_width, line.b_width);
+
+        const double w        = fmax(line.a_width, line.b_width);
+        const Flow   new_flow = (role == erOverhangPerimeter && flow.bridge()) ? flow : flow.with_width(unscale<float>(w) + flow.height() * float(1. - 0.25 * PI));
         if (path.polyline.points.empty()) {
             path.polyline.append(line.a);
             path.polyline.append(line.b);
             // Convert from spacing to extrusion width based on the extrusion model
             // of a square extrusion ended with semi circles.
-            Flow new_flow = (role == erOverhangPerimeter && flow.bridge()) ? flow : flow.with_width(unscale<float>(w) + flow.height() * float(1. - 0.25 * PI));
             #ifdef SLIC3R_DEBUG
             printf("  filling %f gap\n", flow.width);
             #endif
@@ -76,10 +76,11 @@ ExtrusionPaths thick_polyline_to_extrusion_paths(const ThickPolyline &thick_poly
             path.width       = new_flow.width();
             path.height      = new_flow.height();
         } else {
-            thickness_delta = fabs(scale_(flow.width()) - w);
+            assert(path.width >= EPSILON);
+            thickness_delta = scaled<double>(fabs(path.width - new_flow.width()));
             if (thickness_delta <= merge_tolerance) {
-                // the width difference between this line and the current flow width is 
-                // within the accepted tolerance
+                // the width difference between this line and the current flow
+                // (of the previous line) width is within the accepted tolerance
                 path.polyline.append(line.b);
             } else {
                 // we need to initialize a new line