diff --git a/lib/galaxy/webapps/galaxy/api/__init__.py b/lib/galaxy/webapps/galaxy/api/__init__.py
index 93b4fa0b9da3..267f483115cd 100644
--- a/lib/galaxy/webapps/galaxy/api/__init__.py
+++ b/lib/galaxy/webapps/galaxy/api/__init__.py
@@ -8,7 +8,6 @@
     Any,
     AsyncGenerator,
     cast,
-    MutableMapping,
     NamedTuple,
     Optional,
     Tuple,
@@ -21,6 +20,7 @@
 )
 
 from a2wsgi.wsgi import build_environ
+from a2wsgi.wsgi_typing import Environ
 from fastapi import (
     APIRouter,
     Form,
@@ -205,7 +205,7 @@ class GalaxyASGIRequest(GalaxyAbstractRequest):
 
     def __init__(self, request: Request):
         self.__request = request
-        self.__environ: Optional[MutableMapping[str, Any]] = None
+        self.__environ: Optional[Environ] = None
 
     @property
     def base(self) -> str:
@@ -224,7 +224,7 @@ def host(self) -> str:
         return self.__request.base_url.netloc
 
     @property
-    def environ(self) -> MutableMapping[str, Any]:
+    def environ(self) -> Environ:
         """
         Fallback WSGI environ.
 
diff --git a/lib/galaxy/webapps/galaxy/fast_app.py b/lib/galaxy/webapps/galaxy/fast_app.py
index 792a0a5f56d0..5ad703bd10dd 100644
--- a/lib/galaxy/webapps/galaxy/fast_app.py
+++ b/lib/galaxy/webapps/galaxy/fast_app.py
@@ -181,7 +181,7 @@ def initialize_fast_app(gx_wsgi_webapp, gx_app):
     include_legacy_openapi(app, gx_app)
     wsgi_handler = WSGIMiddleware(gx_wsgi_webapp)
     gx_app.haltables.append(("WSGI Middleware threadpool", wsgi_handler.executor.shutdown))
-    app.mount("/", wsgi_handler)
+    app.mount("/", wsgi_handler)  # type: ignore[arg-type]
     if gx_app.config.galaxy_url_prefix != "/":
         parent_app = FastAPI()
         parent_app.mount(gx_app.config.galaxy_url_prefix, app=app)
diff --git a/lib/galaxy/webapps/reports/fast_app.py b/lib/galaxy/webapps/reports/fast_app.py
index fb343e528f89..73d663bbc7b9 100644
--- a/lib/galaxy/webapps/reports/fast_app.py
+++ b/lib/galaxy/webapps/reports/fast_app.py
@@ -22,5 +22,6 @@ def initialize_fast_app(gx_webapp):
     add_request_id_middleware(app)
     include_all_package_routers(app, "galaxy.webapps.reports.api")
     wsgi_handler = WSGIMiddleware(gx_webapp)
-    app.mount("/", wsgi_handler)
+    # https://github.com/abersheeran/a2wsgi/issues/44
+    app.mount("/", wsgi_handler)  # type: ignore[arg-type]
     return app
diff --git a/lib/tool_shed/webapp/fast_app.py b/lib/tool_shed/webapp/fast_app.py
index d4429255017e..ba094c74ec2c 100644
--- a/lib/tool_shed/webapp/fast_app.py
+++ b/lib/tool_shed/webapp/fast_app.py
@@ -193,7 +193,8 @@ def mount_static(directory: Path):
     include_all_package_routers(app, routes_package)
     wsgi_handler = WSGIMiddleware(gx_webapp)
     tool_shed_app.haltables.append(("WSGI Middleware threadpool", wsgi_handler.executor.shutdown))
-    app.mount("/", wsgi_handler)
+    # https://github.com/abersheeran/a2wsgi/issues/44
+    app.mount("/", wsgi_handler)  # type: ignore[arg-type]
     return app
 
 
diff --git a/test/unit/webapps/test_send_file.py b/test/unit/webapps/test_send_file.py
index 4736e3703293..1130e6c8804c 100644
--- a/test/unit/webapps/test_send_file.py
+++ b/test/unit/webapps/test_send_file.py
@@ -29,7 +29,8 @@ def wsgi_application(env, start_response):
         return send_file(start_response, trans, fh)
 
     app = FastAPI()
-    app.mount("/test/send_file", WSGIMiddleware(wsgi_application))
+    # https://github.com/abersheeran/a2wsgi/issues/44
+    app.mount("/test/send_file", WSGIMiddleware(wsgi_application))  # type: ignore[arg-type]
     return app