diff --git a/src/lv_core/lv_obj.c b/src/lv_core/lv_obj.c
index a8daedc8b..a0020abea 100644
--- a/src/lv_core/lv_obj.c
+++ b/src/lv_core/lv_obj.c
@@ -1200,7 +1200,9 @@ void lv_obj_set_ext_click_area(lv_obj_t * obj, lv_coord_t left, lv_coord_t right
 void lv_obj_set_style(lv_obj_t * obj, const lv_style_t * style)
 {
     LV_ASSERT_OBJ(obj, LV_OBJX_NAME);
-    LV_ASSERT_STYLE(style);
+    if(style) {
+        LV_ASSERT_STYLE(style);
+    }
 
     obj->style_p = style;
 
diff --git a/src/lv_draw/lv_draw.h b/src/lv_draw/lv_draw.h
index 865a29a5a..f46fe3ed1 100644
--- a/src/lv_draw/lv_draw.h
+++ b/src/lv_draw/lv_draw.h
@@ -27,7 +27,7 @@ extern "C" {
  *      DEFINES
  *********************/
 #ifndef LV_DRAW_BUF_MAX_NUM
-#define LV_DRAW_BUF_MAX_NUM    12
+#define LV_DRAW_BUF_MAX_NUM    16
 #endif
 
 /**********************
diff --git a/src/lv_themes/lv_theme_mono.c b/src/lv_themes/lv_theme_mono.c
index 54046fa37..bea4dced6 100644
--- a/src/lv_themes/lv_theme_mono.c
+++ b/src/lv_themes/lv_theme_mono.c
@@ -127,9 +127,9 @@ static void label_init(void)
 {
 #if LV_USE_LABEL != 0
 
-    theme.style.label.prim = NULL;
-    theme.style.label.sec  = NULL;
-    theme.style.label.hint = NULL;
+    theme.style.label.prim = &light_plain;
+    theme.style.label.sec  = &light_plain;
+    theme.style.label.hint = &light_plain;
 #endif
 }
 
@@ -145,7 +145,7 @@ static void img_init(void)
 static void line_init(void)
 {
 #if LV_USE_LINE != 0
-    theme.style.line.decor = NULL;
+    theme.style.line.decor = &light_plain;
 #endif
 }