diff --git a/adala/utils/parse.py b/adala/utils/parse.py
index 0a6f7880..7b7052d5 100644
--- a/adala/utils/parse.py
+++ b/adala/utils/parse.py
@@ -1,20 +1,24 @@
+import logging
 import re
 import string
-import logging
+from collections import defaultdict
+from enum import Enum
 from typing import (
-    List,
-    TypedDict,
+    Annotated,
+    Any,
+    DefaultDict,
     Dict,
+    Generator,
+    Iterable,
+    List,
+    Literal,
+    Mapping,
     Optional,
+    TypedDict,
     Union,
-    Literal,
-    Iterable,
-    Generator,
-    Any,
 )
-from enum import Enum
-from pydantic import BaseModel, Field
-from collections import defaultdict
+
+from pydantic import BaseModel, Field, validator
 
 logger = logging.getLogger(__name__)
 
@@ -314,16 +318,26 @@ class MessagesBuilder(BaseModel):
     instruction_first: bool = True
     extra_fields: Dict[str, Any] = Field(default_factory=dict)
     split_into_chunks: bool = False
-    input_field_types: Optional[Dict[str, MessageChunkType]] = Field(default=None)
+    input_field_types: Optional[
+        DefaultDict[
+            str,
+            Annotated[
+                MessageChunkType, Field(default_factory=lambda: MessageChunkType.TEXT)
+            ],
+        ]
+    ] = Field(default_factory=lambda: defaultdict(lambda: MessageChunkType.TEXT))
+
+    @validator("input_field_types", pre=True)
+    def set_default_input_field_types(cls, value):
+        if value is None:
+            return defaultdict(lambda: MessageChunkType.TEXT)
+        return value
 
     def get_messages(self, payload: Dict[str, Any]):
         if self.split_into_chunks:
-            input_field_types = self.input_field_types or defaultdict(
-                lambda: MessageChunkType.TEXT
-            )
             user_prompt = split_message_into_chunks(
                 input_template=self.user_prompt_template,
-                input_field_types=input_field_types,
+                input_field_types=self.input_field_types,
                 **payload,
                 **self.extra_fields,
             )