diff --git a/involute_gears.scad b/involute_gears.scad
index 2a6eb19..8be332f 100644
--- a/involute_gears.scad
+++ b/involute_gears.scad
@@ -364,7 +364,7 @@ module gear (
 		{
 			difference ()
 			{
-				linear_exturde_flat_option(flat=flat, height=rim_thickness, convexity=10, twist=twist)
+				linear_extrude_flat_option(flat=flat, height=rim_thickness, convexity=10, twist=twist)
 				gear_shape (
 					number_of_teeth,
 					pitch_radius = pitch_radius,
@@ -379,28 +379,28 @@ module gear (
 					cylinder (r=rim_radius,h=rim_thickness-gear_thickness+1);
 			}
 			if (gear_thickness > rim_thickness)
-				linear_exturde_flat_option(flat=flat, height=gear_thickness)
+				linear_extrude_flat_option(flat=flat, height=gear_thickness)
 				circle (r=rim_radius);
 			if (flat == false && hub_thickness > gear_thickness)
 				translate ([0,0,gear_thickness])
-				linear_exturde_flat_option(flat=flat, height=hub_thickness-gear_thickness)
+				linear_extrude_flat_option(flat=flat, height=hub_thickness-gear_thickness)
 				circle (r=hub_diameter/2);
 		}
 		translate ([0,0,-1])
-		linear_exturde_flat_option(flat =flat, height=2+max(rim_thickness,hub_thickness,gear_thickness))
+		linear_extrude_flat_option(flat =flat, height=2+max(rim_thickness,hub_thickness,gear_thickness))
 		circle (r=bore_diameter/2);
 		if (circles>0)
 		{
 			for(i=[0:circles-1])
 				rotate([0,0,i*360/circles])
 				translate([circle_orbit_diameter/2,0,-1])
-				linear_exturde_flat_option(flat =flat, height=max(gear_thickness,rim_thickness)+3)
+				linear_extrude_flat_option(flat =flat, height=max(gear_thickness,rim_thickness)+3)
 				circle(r=circle_diameter/2);
 		}
 	}
 }
 
-module linear_exturde_flat_option(flat =false, height = 10, center = false, convexity = 2, twist = 0)
+module linear_extrude_flat_option(flat =false, height = 10, center = false, convexity = 2, twist = 0)
 {
 	if(flat==false)
 	{