diff --git a/src/libslic3r/LayerRegion.cpp b/src/libslic3r/LayerRegion.cpp
index dfae5f1882..0abe27a809 100644
--- a/src/libslic3r/LayerRegion.cpp
+++ b/src/libslic3r/LayerRegion.cpp
@@ -386,10 +386,12 @@ void LayerRegion::prepare_fill_surfaces()
     bool spiral_vase = this->layer()->object()->print()->config().spiral_vase;
 
     // if no solid layers are requested, turn top/bottom surfaces to internal
+    // For Lightning infill, infill_only_where_needed is ignored because both
+    // do a similar thing, and their combination doesn't make much sense.
     if (! spiral_vase && this->region().config().top_solid_layers == 0) {
         for (Surface &surface : this->fill_surfaces.surfaces)
             if (surface.is_top())
-                surface.surface_type = this->layer()->object()->config().infill_only_where_needed ? stInternalVoid : stInternal;
+                surface.surface_type = this->layer()->object()->config().infill_only_where_needed && this->region().config().fill_pattern != ipLightning ? stInternalVoid : stInternal;
     }
     if (this->region().config().bottom_solid_layers == 0) {
         for (Surface &surface : this->fill_surfaces.surfaces)
diff --git a/src/libslic3r/PrintObject.cpp b/src/libslic3r/PrintObject.cpp
index 6ec27ea95b..5cebbb0566 100644
--- a/src/libslic3r/PrintObject.cpp
+++ b/src/libslic3r/PrintObject.cpp
@@ -1733,7 +1733,14 @@ bool PrintObject::update_layer_height_profile(const ModelObject &model_object, c
 // fill_surfaces but we only turn them into VOID surfaces, thus preserving the boundaries.
 void PrintObject::clip_fill_surfaces()
 {
-    if (! m_config.infill_only_where_needed.value)
+    bool has_lightning_infill = false;
+    for (size_t region_id = 0; region_id < this->num_printing_regions(); ++region_id)
+        if (const PrintRegionConfig &config = this->printing_region(region_id).config(); config.fill_density > 0 && config.fill_pattern == ipLightning)
+            has_lightning_infill = true;
+
+    // For Lightning infill, infill_only_where_needed is ignored because both
+    // do a similar thing, and their combination doesn't make much sense.
+    if (! m_config.infill_only_where_needed.value || has_lightning_infill)
         return;
     bool has_infill = false;
     for (size_t i = 0; i < this->num_printing_regions(); ++ i)