diff --git a/lib/Slic3r/Print/Object.pm b/lib/Slic3r/Print/Object.pm
index 51527d0f6..6ab07bd6b 100644
--- a/lib/Slic3r/Print/Object.pm
+++ b/lib/Slic3r/Print/Object.pm
@@ -776,7 +776,7 @@ sub generate_support_material {
             );
             $layers_contact_areas{$i} = [
                 map $_->simplify($flow->scaled_spacing), 
-                    collapse_ex([ map @$_, @{$layers_contact_areas{$i}} ], $flow->scaled_width),
+                    @{collapse_ex([ map @$_, @{$layers_contact_areas{$i}} ], $flow->scaled_width)},
             ];
             
             # to define interface regions of this layer we consider the overhangs of all the upper layers
@@ -790,7 +790,7 @@ sub generate_support_material {
             );
             $layers_interfaces{$i} = [
                 map $_->simplify($flow->scaled_spacing), 
-                    collapse_ex([ map @$_, @{$layers_interfaces{$i}} ], $flow->scaled_width),
+                    @{collapse_ex([ map @$_, @{$layers_interfaces{$i}} ], $flow->scaled_width)},
             ];
             
             # generate support material in current layer (for upper layers)
@@ -812,7 +812,7 @@ sub generate_support_material {
             );
             $layers{$i} = [
                 map $_->simplify($flow->scaled_spacing), 
-                    collapse_ex([ map @$_, @{$layers{$i}} ], $flow->scaled_width),
+                    @{collapse_ex([ map @$_, @{$layers{$i}} ], $flow->scaled_width)},
             ];
             
             # get layer overhangs and put them into queue for adding support inside lower layers;