diff --git a/ormar/queryset/utils.py b/ormar/queryset/utils.py
index 9c84817..b86c1c4 100644
--- a/ormar/queryset/utils.py
+++ b/ormar/queryset/utils.py
@@ -17,7 +17,7 @@ if TYPE_CHECKING:  # pragma no cover
     from ormar import Model, BaseField
 
 
-def to_str(val: Union[bytes, str, int]):
+def to_str(val: Union[bytes, str, int]) -> str:
     """ convert bytes to str simply """
     if isinstance(val, bytes):
         return val.decode("utf-8")
diff --git a/tests/test_queries/test_queryset_level_methods.py b/tests/test_queries/test_queryset_level_methods.py
index 52cced5..9aac707 100644
--- a/tests/test_queries/test_queryset_level_methods.py
+++ b/tests/test_queries/test_queryset_level_methods.py
@@ -42,7 +42,7 @@ class ToDo(ormar.Model):
     id: int = ormar.Integer(primary_key=True)
     text: str = ormar.String(max_length=500)
     completed: bool = ormar.Boolean(default=False)
-    pairs: List[str] = ormar.JSON(default=[])
+    pairs: pydantic.Json = ormar.JSON(default=[])
 
 
 class Category(ormar.Model):