diff --git a/indico/http/serialization.py b/indico/http/serialization.py
index 7038e8e0..98c68d92 100644
--- a/indico/http/serialization.py
+++ b/indico/http/serialization.py
@@ -1,6 +1,7 @@
 """
 Handles deserialization / decoding of responses
 """
+
 import gzip
 import io
 import json
@@ -8,6 +9,7 @@
 import traceback
 from collections import defaultdict
 from email.message import EmailMessage
+from typing import Dict, Tuple
 
 from indico.errors import IndicoDecodingError
 
@@ -42,6 +44,7 @@ def deserialize(response, force_json=False, force_decompress=False):
             content_type, charset, content.decode("ascii", "ignore")
         )
 
+
 async def aio_deserialize(response, force_json=False, force_decompress=False):
     content_type, params = parse_header(response.headers.get("Content-Type"))
     content = await response.read()
@@ -63,11 +66,13 @@ async def aio_deserialize(response, force_json=False, force_decompress=False):
             content_type, charset, content.decode("ascii", "ignore")
         )
 
-def parse_header(header: str) -> tuple[str, dict[str, str]]:
+
+def parse_header(header: str) -> Tuple[str, Dict[str, str]]:
     email = EmailMessage()
     email["Content-Type"] = header
     return email.get_content_type(), email["Content-Type"].params
 
+
 def raw_bytes(content, *args, **kwargs):
     return content
 
diff --git a/indico/queries/model_export.py b/indico/queries/model_export.py
index 197229ba..e802c10c 100644
--- a/indico/queries/model_export.py
+++ b/indico/queries/model_export.py
@@ -1,3 +1,5 @@
+from typing import List, Optional, Union
+
 from indico.client.request import Delay, GraphQLRequest, RequestChain
 from indico.types.model_export import ModelExport
 
@@ -36,13 +38,13 @@ class CreateModelExport(RequestChain):
         request_interval (int | float): the interval between requests in seconds. Defaults to 5.
     """
 
-    previous: ModelExport | None = None
+    previous: Optional[ModelExport] = None
 
     def __init__(
         self,
         model_id: int,
         wait: bool = True,
-        request_interval: int | float = 5,
+        request_interval: Union[int, float] = 5,
     ):
         self.wait = wait
         self.model_id = model_id
@@ -91,14 +93,14 @@ class GetModelExports(GraphQLRequest):
         "createdBy",
     ]
 
-    def __init__(self, export_ids: list[int], with_signed_url: bool = False):
+    def __init__(self, export_ids: List[int], with_signed_url: bool = False):
         if with_signed_url:
             self._base_fields.append("signedUrl")
 
         query_with_fields = self.query.replace("{fields}", "\n".join(self._base_fields))
         super().__init__(query_with_fields, variables={"exportIds": export_ids})
 
-    def process_response(self, response) -> list[ModelExport]:
+    def process_response(self, response) -> List[ModelExport]:
         return [
             ModelExport(**export)
             for export in super().process_response(response)["modelExports"][
diff --git a/indico/queries/model_import.py b/indico/queries/model_import.py
index afdcfff0..b4ab038e 100644
--- a/indico/queries/model_import.py
+++ b/indico/queries/model_import.py
@@ -1,4 +1,4 @@
-from typing import Generator
+from typing import Generator, Optional, Union
 
 import requests
 
@@ -100,7 +100,10 @@ class UploadStaticModelExport(RequestChain):
     """
 
     def __init__(
-        self, file_path: str, auto_process: bool = False, workflow_id: int | None = None
+        self,
+        file_path: str,
+        auto_process: bool = False,
+        workflow_id: Optional[int] = None,
     ):
         self.file_path = file_path
         self.auto_process = auto_process
@@ -111,7 +114,7 @@ def __init__(
 
         self.workflow_id = workflow_id
 
-    def requests(self) -> Generator[str | Job, None, None]:
+    def requests(self) -> Generator[Union[str, Job], None, None]:
         if self.auto_process:
             yield _UploadSMExport(self.file_path)
             yield ProcessStaticModelExport(
diff --git a/indico/queries/submission.py b/indico/queries/submission.py
index 1e150a1e..ccdd8265 100644
--- a/indico/queries/submission.py
+++ b/indico/queries/submission.py
@@ -490,7 +490,7 @@ class SubmitReview(GraphQLRequest):
     def __init__(
         self,
         submission: Union[int, Submission],
-        changes: Dict | List = None,
+        changes: Union[Dict, List] = None,
         rejected: bool = False,
         force_complete: bool = None,
     ):
diff --git a/indico/queries/workflow_components.py b/indico/queries/workflow_components.py
index 46b89a13..396bd84e 100644
--- a/indico/queries/workflow_components.py
+++ b/indico/queries/workflow_components.py
@@ -1,4 +1,4 @@
-from typing import Any, List
+from typing import Any, Dict, List, Optional
 
 import jsons
 
@@ -71,7 +71,7 @@ def __init__(
         after_component_link: int,
         workflow_id: int,
         component: dict,
-        blueprint_id: int | None = None,
+        blueprint_id: Optional[int] = None,
     ):
         super().__init__(
             self.query,
@@ -464,12 +464,12 @@ class AddStaticModelComponent(RequestChain):
     def __init__(
         self,
         workflow_id: int,
-        after_component_id: int | None = None,
-        after_component_link_id: int | None = None,
-        static_component_config: dict[str, Any] | None = None,
-        component_name: str | None = None,
+        after_component_id: Optional[int] = None,
+        after_component_link_id: Optional[int] = None,
+        static_component_config: Optional[Dict[str, Any]] = None,
+        component_name: Optional[str] = None,
         auto_process: bool = False,
-        export_file: str | None = None,
+        export_file: Optional[str] = None,
     ):
         if not export_file and auto_process:
             raise IndicoInputError("Must provide export_file if auto_process is True.")