diff --git a/CHANGELOG.md b/CHANGELOG.md
index c8c809c..465e267 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,4 @@
-## v4.9.0
+## v4.9.1
 - Fixing nested diffable POD structs being incorrectly marked as clean in GetDiff
 
 ## v4.8.2
diff --git a/tpl/macro.twig b/tpl/macro.twig
index 7aff355..d1e65ce 100644
--- a/tpl/macro.twig
+++ b/tpl/macro.twig
@@ -459,7 +459,7 @@ public class {{o.name}} : IRpc
       }
       else if(old > item)
       {
-        item.SetDirtyMask();
+        item.SetDirtyMaskDeep();
         if(changed != null)
           changed.Add(item);
         i++;
@@ -483,7 +483,7 @@ public class {{o.name}} : IRpc
     for(; i < items.Count; i++)
     {
       var item = items[i];
-      item.SetDirtyMask();
+      item.SetDirtyMaskDeep();
       if(changed != null)
         changed.Add(item);
       has_diff = true;
@@ -532,26 +532,54 @@ public class {{o.name}} : IRpc
 {{has_token(o, 'bitfields')?'CompareAndMarkFields':'IsEqual'}}
 {%- endmacro %}
 
-{%- macro field_compare(o, f, field_idx) -%}
+{% macro field_compare_array_bitfields_nested_diffable(o, f, field_idx) %}
+    {
+      int {{f.name}}_count_a = a.{{f.name}} == null ? 0 : a.{{f.name}}.Count;
+      int {{f.name}}_count_b = b.{{f.name}} == null ? 0 : b.{{f.name}}.Count;
 
-  {% if f.type is instanceof('\\mtgArrType') ~%}
-    {% if has_token(o, 'bitfields') ~%}
+      //For NESTED arrays of DIFFABLE structs:
+      //for DB compatibility we must add the WHOLE ARRAY to the diff if ANY ELEMENT of the array has changed.
+      //That means marking each element's fields_mask as dirty
+
+      //Changed size means the array has changed, no furhter checks required.
+      bool {{f.name}}_equal = {{f.name}}_count_a == {{f.name}}_count_b;
+
+      //For same size arrays - check contents for changes.
+      if({{f.name}}_equal)
+      {
+        for(int i=0;i<{{f.name}}_count_a && i<{{f.name}}_count_b;++i)
+        {
+          var tmp_{{f.name}} = a.{{f.name}}[i];
+          if(!CompareAndMarkFields(ref tmp_{{f.name}}, b.{{f.name}}[i]))
+          {
+            {{f.name}}_equal = false;
+            break;
+          }
+        }
+      }
+
+      //If change detected - mark top-level field as changed and add the whole array to the diff
+      if(!{{f.name}}_equal)
+      {
+        MetaIO.SetFieldDirty(ref a.fields_mask, {{field_idx}});
+        for(int i=0; i<{{f.name}}_count_a;++i)
+        {
+          var tmp_{{f.name}} = a.{{f.name}}[i];
+          tmp_{{f.name}}.SetDirtyMaskDeep();
+          a.{{f.name}}[i] = tmp_{{f.name}};
+          is_equal = false;
+        }
+      }
+    }
+{%- endmacro %}
+
+{% macro field_compare_array_bitfields_nested_plain(o, f, field_idx) %}
     if(a.{{f.name}} == null ||
        b.{{f.name}} == null ||
        a.{{f.name}}.Count != b.{{f.name}}.Count)
     {
       MetaIO.SetFieldDirty(ref a.fields_mask, {{field_idx}});
       is_equal = false;
-
-      {% if has_token(f.type.value, 'bitfields') ~%}
-      //TODO: inefficient but reliable: marking the WHOLE collection as dirty when size changes
-      for(int i=0;i<a.{{f.name}}.Count;++i)
-      {
-          var tmp_{{f.name}} = a.{{f.name}}[i];
-          tmp_{{f.name}}.fields_mask = FieldsMask.MakeDirty(tmp_{{f.name}}.GetFieldsCount());
-          a.{{f.name}}[i] = tmp_{{f.name}};
-      }
-      {% endif ~%}
     }
     else
     {
@@ -575,7 +603,9 @@ public class {{o.name}} : IRpc
         {%- endif -%}
       }
     }
-    {% else ~%}
+{%- endmacro %}
+
+{% macro field_compare_array_plain(o, f, field_idx) %}
     if(a.{{f.name}} == null || 
        b.{{f.name}} == null || 
        a.{{f.name}}.Count != b.{{f.name}}.Count) 
@@ -591,6 +621,19 @@ public class {{o.name}} : IRpc
           return false;
       {%- endif -%}
     }
+{%- endmacro %}
+
+{%- macro field_compare(o, f, field_idx) -%}
+
+  {% if f.type is instanceof('\\mtgArrType') ~%}
+    {% if has_token(o, 'bitfields') ~%}
+      {% if has_token(f.type.value, 'bitfields') ~%}
+        {{_self.field_compare_array_bitfields_nested_diffable(o, f, field_idx)}}
+      {% else ~%}
+        {{_self.field_compare_array_bitfields_nested_plain(o, f, field_idx)}}
+      {% endif ~%}
+    {% else ~%}
+      {{_self.field_compare_array_plain(o, f, field_idx)}}
     {% endif ~%}
 
   {% elseif f.type is instanceof('\\mtgMetaStruct') ~%}
@@ -730,4 +773,3 @@ public interface {{ai.interfacename}}
 {% endfor %}
 {%- endfor ~%}
 {% endmacro %}
-