diff --git a/src/gui/core/canvas.cpp b/src/gui/core/canvas.cpp
index c909155ff1e1..fc8b3c1182a4 100644
--- a/src/gui/core/canvas.cpp
+++ b/src/gui/core/canvas.cpp
@@ -473,6 +473,9 @@ class line_shape : public canvas::shape
  *                                     available. An alpha of 255 is fully
  *                                     transparent. Omitted values are set to
  *                                     0. $
+ *     f_color &                       A string which contains a color, or a formula
+ *                                     which evaluates to a list containing the color's
+ *                                     components. $
  *
  *     font_style &                    A string which contains the style of the
  *                                     font: