diff --git a/docling/datamodel/document.py b/docling/datamodel/document.py
index 43894b0..93dfd1a 100644
--- a/docling/datamodel/document.py
+++ b/docling/datamodel/document.py
@@ -283,6 +283,13 @@ 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":
+                if obj.suffixes[-1].lower() == ".xlsx":
+                    mime = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
+                elif obj.suffixes[-1].lower() == ".docx":
+                    mime = "application/vnd.openxmlformats-officedocument.wordprocessingml.document"
+                elif obj.suffixes[-1].lower() == ".pptx":
+                    mime = "application/vnd.openxmlformats-officedocument.presentationml.presentation"
 
         elif isinstance(obj, DocumentStream):
             content = obj.stream.read(8192)