diff --git a/src/openai/cli/_progress.py b/src/openai/cli/_progress.py
index 390aaa9df..810b58c9f 100644
--- a/src/openai/cli/_progress.py
+++ b/src/openai/cli/_progress.py
@@ -1,48 +1,35 @@
 from __future__ import annotations
-
 import io
 from typing import Callable
 from typing_extensions import override
-
+import tqdm
 
 class CancelledError(Exception):
     def __init__(self, msg: str) -> None:
-        self.msg = msg
         super().__init__(msg)
 
-    @override
-    def __str__(self) -> str:
-        return self.msg
-
-    __repr__ = __str__
-
-
 class BufferReader(io.BytesIO):
     def __init__(self, buf: bytes = b"", desc: str | None = None) -> None:
         super().__init__(buf)
-        self._len = len(buf)
         self._progress = 0
         self._callback = progress(len(buf), desc=desc)
 
     def __len__(self) -> int:
-        return self._len
+        return len(self.getvalue())
 
     @override
     def read(self, n: int | None = -1) -> bytes:
-        chunk = io.BytesIO.read(self, n)
+        chunk = super().read(n)
         self._progress += len(chunk)
 
         try:
             self._callback(self._progress)
-        except Exception as e:  # catches exception from the callback
-            raise CancelledError("The upload was cancelled: {}".format(e))
+        except Exception as e:
+            raise CancelledError(f"The upload was cancelled: {e}")
 
         return chunk
 
-
 def progress(total: float, desc: str | None) -> Callable[[float], None]:
-    import tqdm
-
     meter = tqdm.tqdm(total=total, unit_scale=True, desc=desc)
 
     def incr(progress: float) -> None:
@@ -54,6 +41,5 @@ def incr(progress: float) -> None:
 
     return incr
 
-
 def MB(i: int) -> int:
-    return int(i // 1024**2)
+    return i // 1024**2
diff --git a/tests/test_files.py b/tests/test_files.py
index 15d5c6a81..17c65584a 100644
--- a/tests/test_files.py
+++ b/tests/test_files.py
@@ -46,6 +46,6 @@ def test_string_not_allowed() -> None:
     with pytest.raises(TypeError, match="Expected file types input to be a FileContent type or to be a tuple"):
         to_httpx_files(
             {
-                "file": "foo",  # type: ignore
+                "file": "foo",
             }
         )