diff --git a/src/extra/widgets/calendar/lv_calendar_header_arrow.c b/src/extra/widgets/calendar/lv_calendar_header_arrow.c
index c31deff4d..c38e09e89 100644
--- a/src/extra/widgets/calendar/lv_calendar_header_arrow.c
+++ b/src/extra/widgets/calendar/lv_calendar_header_arrow.c
@@ -25,7 +25,7 @@
 /**********************
  *  STATIC PROTOTYPES
  **********************/
-static void my_constructor(lv_obj_class_t * class_p, lv_obj_t * obj);
+static void my_constructor(const lv_obj_class_t * class_p, lv_obj_t * obj);
 static void month_event_cb(lv_event_t * e);
 
 /**********************
@@ -61,7 +61,7 @@ lv_obj_t * lv_calendar_header_arrow_create(lv_obj_t * parent, lv_obj_t * calenda
  *  STATIC FUNCTIONS
  **********************/
 
-static void my_constructor(lv_obj_class_t * class_p, lv_obj_t * obj)
+static void my_constructor(const lv_obj_class_t * class_p, lv_obj_t * obj)
 {
     LV_TRACE_OBJ_CREATE("begin");
 
diff --git a/src/extra/widgets/calendar/lv_calendar_header_dropdown.c b/src/extra/widgets/calendar/lv_calendar_header_dropdown.c
index 7ee437f8e..18af0d94a 100644
--- a/src/extra/widgets/calendar/lv_calendar_header_dropdown.c
+++ b/src/extra/widgets/calendar/lv_calendar_header_dropdown.c
@@ -24,7 +24,7 @@
 /**********************
  *  STATIC PROTOTYPES
  **********************/
-static void my_constructor(lv_obj_class_t * class_p, lv_obj_t * obj);
+static void my_constructor(const lv_obj_class_t * class_p, lv_obj_t * obj);
 static void year_event_cb(lv_event_t * e);
 static void month_event_cb(lv_event_t * e);
 
@@ -70,7 +70,7 @@ lv_obj_t * lv_calendar_header_dropdown_create(lv_obj_t * parent, lv_obj_t * cale
  *  STATIC FUNCTIONS
  **********************/
 
-static void my_constructor(lv_obj_class_t * class_p, lv_obj_t * obj)
+static void my_constructor(const lv_obj_class_t * class_p, lv_obj_t * obj)
 {
     LV_TRACE_OBJ_CREATE("begin");
 
diff --git a/src/extra/widgets/spinner/lv_spinner.c b/src/extra/widgets/spinner/lv_spinner.c
index 3e32e3b0e..e7dbda456 100644
--- a/src/extra/widgets/spinner/lv_spinner.c
+++ b/src/extra/widgets/spinner/lv_spinner.c
@@ -20,7 +20,7 @@
 /**********************
  *  STATIC PROTOTYPES
  **********************/
-static void lv_spinner_constructor(lv_obj_class_t * class_p, lv_obj_t * obj);
+static void lv_spinner_constructor(const lv_obj_class_t * class_p, lv_obj_t * obj);
 static void arc_anim_start_angle(void * obj, int32_t v);
 static void arc_anim_end_angle(void * obj, int32_t v);
 
@@ -63,7 +63,7 @@ lv_obj_t * lv_spinner_create(lv_obj_t * parent, uint32_t time, uint32_t arc_leng
  *   STATIC FUNCTIONS
  **********************/
 
-static void lv_spinner_constructor(lv_obj_class_t * class_p, lv_obj_t * obj)
+static void lv_spinner_constructor(const lv_obj_class_t * class_p, lv_obj_t * obj)
 {
     LV_TRACE_OBJ_CREATE("begin");