diff --git a/lib/Slic3r/Fill/Concentric.pm b/lib/Slic3r/Fill/Concentric.pm
index 549e33324..718bddd9f 100644
--- a/lib/Slic3r/Fill/Concentric.pm
+++ b/lib/Slic3r/Fill/Concentric.pm
@@ -18,11 +18,14 @@ sub fill_surface {
     my $min_spacing = scale $params{flow_spacing};
     my $distance = $min_spacing / $params{density};
     
-    $distance = $self->adjust_solid_spacing(
-        width       => $bounding_box->[X2] - $bounding_box->[X1],
-        distance    => $distance,
-    ) if $params{density} == 1;
-    my $flow_spacing = unscale $distance;
+    my $flow_spacing;
+    if ($params{density} == 1) {
+        $distance = $self->adjust_solid_spacing(
+            width       => $bounding_box->[X2] - $bounding_box->[X1],
+            distance    => $distance,
+        );
+        $flow_spacing = unscale $distance;
+    }
     
     my @contour_loops = ();
     my @hole_loops = ();
diff --git a/lib/Slic3r/Fill/Rectilinear.pm b/lib/Slic3r/Fill/Rectilinear.pm
index 8eaa3ba08..103e2f835 100644
--- a/lib/Slic3r/Fill/Rectilinear.pm
+++ b/lib/Slic3r/Fill/Rectilinear.pm
@@ -23,11 +23,14 @@ sub fill_surface {
     my $distance_between_lines = $min_spacing / $params{density};
     my $line_oscillation = $distance_between_lines - $min_spacing;
     
-    $distance_between_lines = $self->adjust_solid_spacing(
-        width       => $bounding_box->[X2] - $bounding_box->[X1],
-        distance    => $distance_between_lines,
-    ) if $params{density} == 1;
-    my $flow_spacing = unscale $distance_between_lines;
+    my $flow_spacing;
+    if ($params{density} == 1) {
+        $distance_between_lines = $self->adjust_solid_spacing(
+            width       => $bounding_box->[X2] - $bounding_box->[X1],
+            distance    => $distance_between_lines,
+        );
+        $flow_spacing = unscale $distance_between_lines;
+    }
     
     my $overlap_distance = $Slic3r::nozzle_diameter * 0.20;