diff --git a/Build.PL b/Build.PL
index d64762a1..c6fd4543 100644
--- a/Build.PL
+++ b/Build.PL
@@ -69,8 +69,14 @@ EOF
 my %modules = (%prereqs, %recommends);
 foreach my $module (sort keys %modules) {
     my $version = $modules{$module};
-    system $cpanm, '--sudo', "$module~$version";
+    if ($ENV{SLIC3R_NO_AUTO}) {
+        print "Missing prerequisite $module $version\n"
+            if !eval "use $module $version; 1";
+    } else {
+        system $cpanm, "$module~$version";
+    }
 }
+exit if $ENV{SLIC3R_NO_AUTO};
 
 if (eval "use App::Prove; 1") {
     App::Prove->new->run;
diff --git a/lib/Slic3r/Config.pm b/lib/Slic3r/Config.pm
index 5aed5713..83088f58 100644
--- a/lib/Slic3r/Config.pm
+++ b/lib/Slic3r/Config.pm
@@ -1071,13 +1071,13 @@ sub new_from_cli {
     for (qw(start end layer toolchange)) {
         my $opt_key = "${_}_gcode";
         if ($args{$opt_key}) {
-            die "Invalid value for --${_}-gcode: file does not exist\n"
-                if !-e $args{$opt_key};
-            Slic3r::open(\my $fh, "<", $args{$opt_key})
-                or die "Failed to open $args{$opt_key}\n";
-            binmode $fh, ':utf8';
-            $args{$opt_key} = do { local $/; <$fh> };
-            close $fh;
+            if (-e $args{$opt_key}) {
+                Slic3r::open(\my $fh, "<", $args{$opt_key})
+                    or die "Failed to open $args{$opt_key}\n";
+                binmode $fh, ':utf8';
+                $args{$opt_key} = do { local $/; <$fh> };
+                close $fh;
+            }
         }
     }
     
diff --git a/lib/Slic3r/GCode/Layer.pm b/lib/Slic3r/GCode/Layer.pm
index 5d398f46..26db9fc0 100644
--- a/lib/Slic3r/GCode/Layer.pm
+++ b/lib/Slic3r/GCode/Layer.pm
@@ -44,7 +44,9 @@ sub process_layer {
     $self->gcodegen->move_z_callback(sub {
         $self->gcodegen->move_z_callback(undef);  # circular ref or not?
         return "" if !$Slic3r::Config->layer_gcode;
-        return $Slic3r::Config->replace_options($Slic3r::Config->layer_gcode) . "\n";
+        return $Slic3r::Config->replace_options($Slic3r::Config->layer_gcode, {
+            layer_num => $self->gcodegen->layer->id,
+        }) . "\n";
     });
     
     # extrude skirt
diff --git a/lib/Slic3r/Print/Object.pm b/lib/Slic3r/Print/Object.pm
index e50814f8..8aa833e1 100644
--- a/lib/Slic3r/Print/Object.pm
+++ b/lib/Slic3r/Print/Object.pm
@@ -738,8 +738,8 @@ sub combine_infill {
             my @layerms = map $self->layers->[$_]->regions->[$region_id],
                 ($layer_id - ($combine[$layer_id]-1) .. $layer_id);
             
-            # process internal and internal-solid infill separately
-            for my $type (S_TYPE_INTERNAL, S_TYPE_INTERNALSOLID) {
+            # only combine internal infill
+            for my $type (S_TYPE_INTERNAL) {
                 # we need to perform a multi-layer intersection, so let's split it in pairs
                 
                 # initialize the intersection with the candidates of the lowest layer