diff --git a/xs/src/libslic3r/LayerRegion.cpp b/xs/src/libslic3r/LayerRegion.cpp
index b7d9058fe..1baaa0bef 100644
--- a/xs/src/libslic3r/LayerRegion.cpp
+++ b/xs/src/libslic3r/LayerRegion.cpp
@@ -231,12 +231,13 @@ LayerRegion::prepare_fill_surfaces()
     }
         
     // turn too small internal regions into solid regions according to the user setting
-    if (this->region()->config.fill_density.value > 0) {
+    const float &fill_density = this->region()->config.fill_density;
+    if (fill_density > 0 && fill_density < 100) {
         // scaling an area requires two calls!
-        double min_area = scale_(scale_(this->region()->config.solid_infill_below_area.value));
-        for (Surfaces::iterator surface = this->fill_surfaces.surfaces.begin(); surface != this->fill_surfaces.surfaces.end(); ++surface) {
-            if (surface->surface_type == stInternal && surface->area() <= min_area)
-                surface->surface_type = stInternalSolid;
+        const double min_area = scale_(scale_(this->region()->config.solid_infill_below_area.value));
+        for (Surface &surface : this->fill_surfaces.surfaces) {
+            if (surface.surface_type == stInternal && surface.area() <= min_area)
+                surface.surface_type = stInternalSolid;
         }
     }
 }