diff --git a/lv_objx/lv_canvas.c b/lv_objx/lv_canvas.c
index 895c966a9..9b25c5fe8 100644
--- a/lv_objx/lv_canvas.c
+++ b/lv_objx/lv_canvas.c
@@ -6,6 +6,7 @@
 /*********************
  *      INCLUDES
  *********************/
+#include <stdlib.h>
 #include "lv_canvas.h"
 #if USE_LV_CANVAS != 0
 
@@ -326,6 +327,8 @@ void lv_canvas_draw_circle(lv_obj_t * canvas, lv_coord_t x0, lv_coord_t y0, lv_c
  * @param point1 start point of the line
  * @param point2 end point of the line
  * @param color color of the line
+ *
+ * NOTE: The lv_canvas_draw_line function originates from https://github.com/jb55/bresenham-line.c.
  */
 void lv_canvas_draw_line(lv_obj_t * canvas, lv_point_t point1, lv_point_t point2, lv_color_t color)
 {