diff --git a/proto/ei-scanner b/proto/ei-scanner
index ae42b0c..1f08922 100755
--- a/proto/ei-scanner
+++ b/proto/ei-scanner
@@ -17,7 +17,7 @@ Opcodes for events and request are assigned in order as they
 appear in the XML file.
 """
 
-from typing import Any, Optional, Union, Tuple
+from typing import Any, List, Optional, Tuple, Union
 from pathlib import Path
 from textwrap import dedent
 
@@ -141,7 +141,7 @@ class Message:
     is_destructor: bool = attr.ib(default=False)
     context_type: Optional[str] = attr.ib(default=None)
 
-    arguments: list[Argument] = attr.ib(init=False, factory=list)
+    arguments: List[Argument] = attr.ib(init=False, factory=list)
 
     @context_type.validator  # type: ignore
     def _context_type_validate(self, attr, value):
@@ -254,7 +254,7 @@ class Enum:
     is_bitfield: bool = attr.ib(default=False)
     description: Optional[Description] = attr.ib(default=None)
 
-    entries: list[Entry] = attr.ib(init=False, factory=list)
+    entries: List[Entry] = attr.ib(init=False, factory=list)
 
     @classmethod
     def create(
@@ -301,9 +301,9 @@ class Enum:
 class Interface:
     name: str = attr.ib()
     version: int = attr.ib()
-    requests: list[Request] = attr.ib(init=False, factory=list)
-    events: list[Event] = attr.ib(init=False, factory=list)
-    enums: list[Enum] = attr.ib(init=False, factory=list)
+    requests: List[Request] = attr.ib(init=False, factory=list)
+    events: List[Event] = attr.ib(init=False, factory=list)
+    enums: List[Enum] = attr.ib(init=False, factory=list)
 
     mode: str = attr.ib()  # "ei" or "eis"
     description: Optional[Description] = attr.ib(default=None)
@@ -340,7 +340,7 @@ class Interface:
         return None
 
     @property
-    def outgoing(self) -> list[Message]:
+    def outgoing(self) -> List[Message]:
         """
         Returns the list of messages outgoing from this implementation.
 
@@ -358,7 +358,7 @@ class Interface:
             )
 
     @property
-    def incoming(self) -> list[Message]:
+    def incoming(self) -> List[Message]:
         """
         Returns the list of messages incoming to this implementation.
 
@@ -416,13 +416,13 @@ class Copyright:
 @attr.s
 class Protocol:
     copyright: Optional[str] = attr.ib(default=None)
-    interfaces: list[Interface] = attr.ib(factory=list)
+    interfaces: List[Interface] = attr.ib(factory=list)
 
 
 @attr.s
 class ProtocolParser(xml.sax.handler.ContentHandler):
     component: str = attr.ib()
-    interfaces: list[Interface] = attr.ib(factory=list)
+    interfaces: List[Interface] = attr.ib(factory=list)
     copyright: Optional[Copyright] = attr.ib(init=False, default=None)
 
     current_interface: Optional[Interface] = attr.ib(init=False, default=None)