diff --git a/readme.md b/readme.md
index a28be89..f1e750f 100644
--- a/readme.md
+++ b/readme.md
@@ -2618,8 +2618,8 @@ Timing belt pulleys, both toothed and plain with internal bearings for idlers.
 ### Modules
 | Module | Description |
 |:--- |:--- |
-| `pulley(type)` | Draw a pulley |
-| `pulley_assembly(type)` | Draw a pulley with its grub screws in place |
+| `pulley(type, colour = silver)` | Draw a pulley |
+| `pulley_assembly(type, colour = silver)` | Draw a pulley with its grub screws in place |
 
 ![pulleys](tests/png/pulleys.png)
 
diff --git a/vitamins/pulley.scad b/vitamins/pulley.scad
index 42b88c9..fe1f293 100644
--- a/vitamins/pulley.scad
+++ b/vitamins/pulley.scad
@@ -53,7 +53,7 @@ function pulley_extent(type) = max(pulley_flange_dia(type), pulley_hub_dia(type)
 T_angle = 40;
 GT_r = 0.555;
 
-module pulley(type) { //! Draw a pulley
+module pulley(type, colour = silver) { //! Draw a pulley
     teeth = pulley_teeth(type);
     od = pulley_od(type);
 
@@ -117,7 +117,7 @@ module pulley(type) { //! Draw a pulley
                 rotate([-90, 0, i * -90])
                     cylinder(r = screw_radius(pulley_screw(type)), h = 100);
 
-    color(silver) {
+    color(colour) {
         if(screw_z && screw_z < hl)
             render()
                 difference() {
@@ -140,9 +140,9 @@ module pulley(type) { //! Draw a pulley
     }
 }
 
-module pulley_assembly(type) { //! Draw a pulley with its grub screws in place
+module pulley_assembly(type, colour = silver) { //! Draw a pulley with its grub screws in place
     translate_z(pulley_offset(type)) {
-        pulley(type);
+        pulley(type, colour);
 
         if(pulley_screws(type))
             translate_z(pulley_screw_z(type))