diff --git a/docling/datamodel/document.py b/docling/datamodel/document.py
index fcc37484..70d08b75 100644
--- a/docling/datamodel/document.py
+++ b/docling/datamodel/document.py
@@ -283,9 +283,14 @@ class _DocumentConversionInput(BaseModel):
             if mime is None:  # must guess from
                 with obj.open("rb") as f:
                     content = f.read(1024)  # Read first 1KB
-            if mime is not None and mime.lower() == "application/zip" and obj.suffixes[-1].lower() == ".xlsx":
-                mime = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
-
+            if (
+                mime is not None
+                and mime.lower() == "application/zip"
+                and obj.suffixes[-1].lower() == ".xlsx"
+            ):
+                mime = (
+                    "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
+                )
 
         elif isinstance(obj, DocumentStream):
             content = obj.stream.read(8192)