diff --git a/widgets/imagebox.c b/widgets/imagebox.c
index 3664ece1..f62f53f0 100644
--- a/widgets/imagebox.c
+++ b/widgets/imagebox.c
@@ -133,7 +133,7 @@ luaA_imagebox_newindex(lua_State *L, awesome_token_t token)
         size_t len;
 
       case A_TK_IMAGE:
-        luaA_checkudata(L, -1, &image_class);
+        luaA_checkudataornil(L, -1, &image_class);
         luaA_object_unref_item(L, 1, d->image);
         d->image = luaA_object_ref_item(L, 1, 3);
         break;
diff --git a/widgets/textbox.c b/widgets/textbox.c
index cc9d59a6..e5e63735 100644
--- a/widgets/textbox.c
+++ b/widgets/textbox.c
@@ -346,7 +346,7 @@ luaA_textbox_newindex(lua_State *L, awesome_token_t token)
         d->bg_resize = luaA_checkboolean(L, 3);
         break;
       case A_TK_BG_IMAGE:
-        luaA_checkudata(L, -1, &image_class);
+        luaA_checkudataornil(L, -1, &image_class);
         luaA_object_unref_item(L, 1, d->bg_image);
         d->bg_image = luaA_object_ref_item(L, 1, 3);
         break;