diff --git a/src/arc.scad b/src/arc.scad
index 98db7035..62f85222 100644
--- a/src/arc.scad
+++ b/src/arc.scad
@@ -10,6 +10,6 @@
 
 use <shape_arc.scad>;
 
-module arc(radius, angle, width, width_mode = "LINE_CROSS") {
+module arc(radius, angle, width = 1, width_mode = "LINE_CROSS") {
     polygon(shape_arc(radius, angle, width, width_mode));
 }
\ No newline at end of file