diff --git a/prepline_general/api/general.py b/prepline_general/api/general.py
index 04142dcc..aa581177 100644
--- a/prepline_general/api/general.py
+++ b/prepline_general/api/general.py
@@ -7,6 +7,7 @@
 import mimetypes
 import os
 import secrets
+import zipfile
 from base64 import b64encode
 from concurrent.futures import ThreadPoolExecutor
 from functools import partial
@@ -26,10 +27,12 @@
     status,
 )
 from fastapi.responses import PlainTextResponse, StreamingResponse
+from olefile.olefile import OleFileError  # note: olefile <0.48 does not re-export it at top level
 from pypdf import PageObject, PdfReader, PdfWriter
 from pypdf.errors import FileNotDecryptedError, PdfReadError
 from starlette.datastructures import Headers
 from starlette.types import Send
+from unstructured.errors import UnprocessableEntityError
 
 from prepline_general.api import __version__ as api_version
 from prepline_general.api.filetypes import get_validated_mimetype
@@ -397,6 +400,24 @@ def pipeline_api(
         else:
             elements = partition(**partition_kwargs)  # type: ignore # pyright: ignore[reportGeneralTypeIssues]
 
+    except OleFileError as e:
+        # OleFileError subclasses OSError, so it must be caught before the OSError
+        # handler below. Corrupt or truncated OLE files (.doc, .ppt, .msg) are a
+        # client-side problem and should not surface as a 500.
+        raise HTTPException(
+            status_code=400,
+            detail=f"File does not appear to be a valid OLE file: {e}",
+        )
+    except zipfile.BadZipFile as e:
+        raise HTTPException(
+            status_code=400,
+            detail=f"File does not appear to be a valid OOXML file: {e}",
+        )
+    except UnprocessableEntityError as e:
+        raise HTTPException(
+            status_code=400,
+            detail=str(e),
+        )
     except OSError as e:
         if isinstance(e.args[0], str) and (
             "chipper-fast-fine-tuning is not a local folder" in e.args[0]
diff --git a/pyproject.toml b/pyproject.toml
index 0668cd7e..706325f2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -13,6 +13,8 @@ dependencies = [
     "psutil >=7.0.0, <8.0.0",
     "pypdf >=6.0.0, <7.0.0",
     "requests >=2.32.0, <3.0.0",
+    # imported directly for OleFileError; also a transitive dep of unstructured
+    "olefile >=0.47, <1.0.0",
 ]
 
 [dependency-groups]
diff --git a/test_general/api/test_app.py b/test_general/api/test_app.py
index ac9cb6fb..999e6e4e 100644
--- a/test_general/api/test_app.py
+++ b/test_general/api/test_app.py
@@ -110,6 +110,34 @@ def test_general_api(example_filename, content_type):
     assert len(dfs) > 0
 
 
+@pytest.mark.parametrize(
+    "example_filename, content_type",
+    [
+        ("fake.doc", "application/msword"),
+        (
+            "fake-power-point.pptx",
+            "application/vnd.openxmlformats-officedocument.presentationml.presentation",
+        ),
+    ],
+)
+def test_truncated_binary_documents_return_400(example_filename, content_type):
+    """
+    A truncated binary document is a client-side problem and must return 400,
+    not the catch-all 500. Truncating a valid fixture mid-file corrupts the
+    OLE/ZIP container without changing its detected file type.
+    """
+    client = TestClient(app)
+    test_file_path = Path("sample-docs") / example_filename
+    with open(test_file_path, "rb") as f:
+        data = f.read()
+    response = client.post(
+        MAIN_API_ROUTE,
+        files=[("files", (example_filename, io.BytesIO(data[: len(data) // 2]), content_type))],
+    )
+
+    assert response.status_code == 400
+
+
 def test_metadata_fields_removed():
     """
     Verify that responses do not include coordinates unless requested
diff --git a/uv.lock b/uv.lock
index 576451b6..7e09f575 100644
--- a/uv.lock
+++ b/uv.lock
@@ -2201,6 +2201,7 @@ source = { editable = "." }
 dependencies = [
     { name = "backoff" },
     { name = "fastapi" },
+    { name = "olefile" },
     { name = "pandas" },
     { name = "psutil" },
     { name = "pypdf" },
@@ -2237,6 +2238,7 @@ test = [
 requires-dist = [
     { name = "backoff", specifier = ">=2.2.1,<3.0.0" },
     { name = "fastapi", specifier = ">=0.128.4,<1.0.0" },
+    { name = "olefile", specifier = ">=0.47,<1.0.0" },
     { name = "pandas", specifier = ">=3.0.0,<4.0.0" },
     { name = "psutil", specifier = ">=7.0.0,<8.0.0" },
     { name = "pypdf", specifier = ">=6.0.0,<7.0.0" },