diff --git a/lib/Slic3r/Print.pm b/lib/Slic3r/Print.pm
index ae0965500..90a981c1f 100644
--- a/lib/Slic3r/Print.pm
+++ b/lib/Slic3r/Print.pm
@@ -524,7 +524,7 @@ EOF
             foreach my $expolygon (@current_layer_slices) {
                 my $intersection = intersection_ex(
                     [ map @$_, @previous_layer_slices ],
-                    $expolygon,
+                    [ @$expolygon ],
                 );
                 @$intersection
                     ? push @supported_slices, $expolygon