diff --git a/sql/item.h b/sql/item.h
index a38a25d..32353d5 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -3421,10 +3421,21 @@ class Item_direct_view_ref :public Item_direct_ref
   }
   bool is_null()
   {
+    DBUG_ENTER("Item_direct_view_ref::is_null");
     if (check_null_ref())
-      return 1;
+    {
+      DBUG_PRINT("XXX", ("Item_direct_view_ref: ref null"));
+      DBUG_RETURN(1);
+    }
     else
-      return Item_direct_ref::is_null();
+    {
+      bool res= Item_direct_ref::is_null();
+      if (res)
+        DBUG_PRINT("XXX", ("Item_direct_view_ref: NULL"));
+      else
+        DBUG_PRINT("XXX", ("Item_direct_view_ref: %lld is NOT NULL", val_int()));
+      DBUG_RETURN(res);
+    }
   }
   bool get_date(MYSQL_TIME *ltime, ulonglong fuzzydate)
   {
diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index 998cb1c..e981455 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -4765,10 +4765,16 @@ Item *and_expressions(Item *a, Item *b, Item **org_item)
 
 longlong Item_func_isnull::val_int()
 {
+  DBUG_ENTER("Item_func_isnull::val_int");
   DBUG_ASSERT(fixed == 1);
   if (const_item() && !args[0]->maybe_null)
-    return 0;
-  return args[0]->is_null() ? 1: 0;
+  {
+    DBUG_PRINT("XXX", ("Item_func_isnull: constant 0"));
+    DBUG_RETURN(0);
+  }
+  bool res= args[0]->is_null() ? 1: 0;
+  DBUG_PRINT("XXX", ("Item_func_isnull: result %d", res));
+  DBUG_RETURN(res);
 }