diff --git a/lib/pbio/src/color/util.c b/lib/pbio/src/color/util.c
index 40b73e7d5..265546c03 100644
--- a/lib/pbio/src/color/util.c
+++ b/lib/pbio/src/color/util.c
@@ -5,6 +5,7 @@
 
 #include <pbio/color.h>
 
+// Cost function between two colors a and b. The lower, the closer they are.
 int32_t pbio_get_hsv_cost(const pbio_color_hsv_t *x, const pbio_color_hsv_t *c) {
 
     // Calculate the hue error
@@ -32,7 +33,8 @@ int32_t pbio_get_hsv_cost(const pbio_color_hsv_t *x, const pbio_color_hsv_t *c)
     return hue_error * hue_error + 5 * saturation_error * saturation_error + 2 * value_error * value_error;
 }
 
-int32_t pbio_get_cone_cost(const pbio_color_hsv_t *hsv_a, const pbio_color_hsv_t *hsv_b) {
+// gets squared cartesian distance between hsv colors mapped into a chroma-value-cone
+int32_t pbio_get_cone_cost(const pbio_color_hsv_t *hsv_a, const pbio_color_hsv_t *hsv_b, const int32_t chroma_weight) {
 
     pbio_color_hsv_fix16_t a, b;
     pbio_color_hsv_to_fix16(hsv_a, &a);
diff --git a/pybricks/util_pb/pb_color_map.c b/pybricks/util_pb/pb_color_map.c
index 8772db06c..71d46885d 100644
--- a/pybricks/util_pb/pb_color_map.c
+++ b/pybricks/util_pb/pb_color_map.c
@@ -68,11 +68,6 @@ void pb_color_map_save_default(mp_obj_t *color_map) {
     *color_map = MP_OBJ_FROM_PTR(&pb_color_map_default);
 }
 
-// Cost function between two colors a and b. The lower, the closer they are.
-static int32_t get_hsv_cost(const pbio_color_hsv_t *a, const pbio_color_hsv_t *b) {
-    return pbio_get_cone_cost(a, b);
-}
-
 // Get a discrete color that matches the given hsv values most closely
 mp_obj_t pb_color_map_get_color(mp_obj_t *color_map, pbio_color_hsv_t *hsv) {
 
@@ -90,7 +85,7 @@ mp_obj_t pb_color_map_get_color(mp_obj_t *color_map, pbio_color_hsv_t *hsv) {
     for (size_t i = 0; i < n; i++) {
 
         // Evaluate the cost function
-        cost_now = get_hsv_cost(hsv, pb_type_Color_get_hsv(colors[i]));
+        cost_now = pbio_get_hsv_cost(hsv, pb_type_Color_get_hsv(colors[i]));
 
         // If cost is less than before, update the minimum and the match
         if (cost_now < cost_min) {