diff --git a/lib/Slic3r/Config.pm b/lib/Slic3r/Config.pm
index 257b90b45..41b5fc4f7 100644
--- a/lib/Slic3r/Config.pm
+++ b/lib/Slic3r/Config.pm
@@ -9,6 +9,7 @@ use List::Util qw(first);
 our @Ignore = qw(duplicate_x duplicate_y multiply_x multiply_y support_material_tool acceleration);
 
 my $serialize_comma     = sub { join ',', @{$_[0]} };
+my $serialize_comma_bool = sub { join ',', map $_ // 0, @{$_[0]} };
 my $deserialize_comma   = sub { [ split /,/, $_[0] ] };
 
 our $Options = {
@@ -797,7 +798,7 @@ END
         tooltip => 'This flag enforces a retraction whenever a Z move is done.',
         cli     => 'retract-layer-change!',
         type    => 'bool',
-        serialize   => $serialize_comma,
+        serialize   => $serialize_comma_bool,
         deserialize => $deserialize_comma,
         default => [1],
     },
@@ -806,7 +807,7 @@ END
         tooltip => 'This flag will move the nozzle while retracting to minimize the possible blob on leaky extruders.',
         cli     => 'wipe!',
         type    => 'bool',
-        serialize   => $serialize_comma,
+        serialize   => $serialize_comma_bool,
         deserialize => $deserialize_comma,
         default => [0],
     },