diff --git a/lib/Slic3r/Config.pm b/lib/Slic3r/Config.pm
index b3172572c..dff00f01c 100644
--- a/lib/Slic3r/Config.pm
+++ b/lib/Slic3r/Config.pm
@@ -54,7 +54,7 @@ our $Options = {
     },
     'extrusion_axis' => {
         label   => 'Extrusion axis',
-        cli     => 'extrusion-axis',
+        cli     => 'extrusion-axis=s',
         type    => 's',
     },
     'z_offset' => {