diff --git a/requirements.in b/requirements.in
index 4045e05a..3f2a4d92 100644
--- a/requirements.in
+++ b/requirements.in
@@ -14,7 +14,7 @@ djangorestframework>=3.10.3,<3.16
 importlib-metadata==8.5.0
 jsonschema==4.23.0
 lxml==5.3.1
-marshmallow==3.22.0
+marshmallow==3.26.1
 pydantic==2.10.6
 pyOpenSSL==25.0.0
 pytz==2025.1
diff --git a/requirements.txt b/requirements.txt
index 5920540b..7312abaa 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -42,7 +42,7 @@ lxml==5.3.1
     # via
     #   -r requirements.in
     #   signxml
-marshmallow==3.22.0
+marshmallow==3.26.1
     # via -r requirements.in
 packaging==24.2
     # via marshmallow
diff --git a/src/cl_sii/libs/mm_utils.py b/src/cl_sii/libs/mm_utils.py
index 67c3126a..13eb98ab 100644
--- a/src/cl_sii/libs/mm_utils.py
+++ b/src/cl_sii/libs/mm_utils.py
@@ -96,7 +96,9 @@ def __init__(self, format: Optional[str] = None, **kwargs: Any) -> None:
         # TODO: for 'marshmallow 3', rename 'dateformat' to 'datetimeformat'.
         self.dateformat = format
 
-    def _bind_to_schema(self, field_name: str, schema: marshmallow.Schema) -> None:
+    def _bind_to_schema(
+        self, field_name: str, schema: marshmallow.Schema | marshmallow.Field
+    ) -> None:
         super()._bind_to_schema(field_name, schema)
         self.dateformat = self.dateformat or schema.opts.dateformat