diff --git a/src/python/matrix_client.py b/src/python/matrix_client.py
index cd0b4061..96561453 100644
--- a/src/python/matrix_client.py
+++ b/src/python/matrix_client.py
@@ -11,7 +11,8 @@ from datetime import datetime
 from functools import partial
 from pathlib import Path
 from typing import (
-    Any, BinaryIO, DefaultDict, Dict, Optional, Set, Tuple, Type, Union,
+    Any, AsyncIterable, BinaryIO, DefaultDict, Dict, Optional, Set, Tuple,
+    Type, Union,
 )
 from urllib.parse import urlparse
 from uuid import uuid4
@@ -34,7 +35,8 @@ from .models.items import (
 from .models.model_store import ModelStore
 from .pyotherside_events import AlertRequested
 
-CryptDict = Dict[str, Any]
+UploadData = Union[bytes, BinaryIO, AsyncIterable[bytes]]
+CryptDict  = Dict[str, Any]
 
 
 class MatrixClient(nio.AsyncClient):
@@ -225,7 +227,7 @@ class MatrixClient(nio.AsyncClient):
             content["msgtype"] = "m.image"
 
             content["info"]["w"], content["info"]["h"] = (
-                utils.svg_dimensions(str(path)) if is_svg else
+                utils.svg_dimensions(path) if is_svg else
                 PILImage.open(path).size
             )
 
@@ -508,7 +510,7 @@ class MatrixClient(nio.AsyncClient):
 
         try:
             if is_svg:
-                svg_width, svg_height = utils.svg_dimensions(str(path))
+                svg_width, svg_height = utils.svg_dimensions(path)
 
                 thumb = PILImage.open(io.BytesIO(
                     cairosvg.svg2png(
@@ -581,7 +583,6 @@ class MatrixClient(nio.AsyncClient):
 
         with open(path, "rb") as file:
             mime = utils.guess_mime(file)
-            file.seek(0, 0)
 
             data: Union[BinaryIO, bytes]
 
@@ -604,8 +605,9 @@ class MatrixClient(nio.AsyncClient):
             )
 
 
-    async def upload(self, data, mime: str, filename: Optional[str] = None,
-                    ) -> str:
+    async def upload(
+        self, data: UploadData, mime: str, filename: Optional[str] = None,
+    ) -> str:
         response = await super().upload(data, mime, filename)
 
         if isinstance(response, nio.UploadError):
diff --git a/src/python/utils.py b/src/python/utils.py
index ca533105..c091dbb0 100644
--- a/src/python/utils.py
+++ b/src/python/utils.py
@@ -96,7 +96,11 @@ def guess_mime(file: File) -> str:
     elif isinstance(file, io.IOBase):
         file.seek(0, 0)
 
-    return filetype.guess_mime(file) or "application/octet-stream"
+    try:
+        return filetype.guess_mime(file) or "application/octet-stream"
+    finally:
+        if isinstance(file, io.IOBase):
+            file.seek(0, 0)
 
 
 def plain2html(text: str) -> str: