diff --git a/outpostcli/lfs/storage_class/s3.py b/outpostcli/lfs/storage_class/s3.py
index f00792b..c9802fe 100644
--- a/outpostcli/lfs/storage_class/s3.py
+++ b/outpostcli/lfs/storage_class/s3.py
@@ -176,9 +176,9 @@ def s3_multipart_upload(msg: Dict[str, Any]):
                     parts.append(resp)
                 pass
         complete_resp = complete_multipart_upload(complete_url, parts)
-        if isinstance(complete_resp, LFSException):
+        if isinstance(complete_resp, ProxyLFSException):
             abort_resp = abort_multipart_upload(abort_url)
-            if isinstance(abort_resp, LFSException):
+            if isinstance(abort_resp, ProxyLFSException):
                 write_msg(
                     {
                         "event": "complete",
@@ -210,7 +210,7 @@ def s3_multipart_upload(msg: Dict[str, Any]):
             write_msg({"event": "complete", "oid": oid})
     except LFSException as e:
         abort_resp = abort_multipart_upload(abort_url)
-        if isinstance(abort_resp, LFSException):
+        if isinstance(abort_resp, ProxyLFSException):
             write_msg(
                 {
                     "event": "complete",
@@ -237,7 +237,7 @@ def s3_multipart_upload(msg: Dict[str, Any]):
     except Exception as e:  # noqa: BLE001
         abort_resp = abort_multipart_upload(abort_url)
         _log.error(e, exc_info=True)
-        if isinstance(abort_resp, LFSException):
+        if isinstance(abort_resp, ProxyLFSException):
             write_msg(
                 {
                     "event": "complete",