diff --git a/src/libslic3r/Fill/FillSpiralInset.cpp b/src/libslic3r/Fill/FillSpiralInset.cpp
index 8f0c75ff83..5931e813cf 100644
--- a/src/libslic3r/Fill/FillSpiralInset.cpp
+++ b/src/libslic3r/Fill/FillSpiralInset.cpp
@@ -352,6 +352,16 @@ void FillSpiralInset::_fill_surface_single(const FillParams& params,
     assert(params.use_arachne);
     assert(this->print_config != nullptr && this->print_object_config != nullptr);
 
+    // Internal solid infill must not add Arachne's standalone thin walls: one of those walls can
+    // become the extra centre point after the spiral has finished. Top and bottom surfaces keep
+    // Arachne, including the centre plug handled by generate_spiral_insets().
+    if (params.extrusion_role == erSolidInfill) {
+        Polylines polylines;
+        this->_fill_surface_single(params, thickness_layers, direction, expolygon, polylines);
+        append(thick_polylines_out, to_thick_polylines(std::move(polylines), scaled<coord_t>(this->spacing)));
+        return;
+    }
+
     // Only a solid surface is worth the variable width walls; a sparse one falls back to plain loops.
     if (params.density <= 0.9999f || params.dont_adjust) {
         Polylines polylines;