diff --git a/invokeai/app/services/download/download_default.py b/invokeai/app/services/download/download_default.py
index 56197dcfb35..bc7cfb7b0df 100644
--- a/invokeai/app/services/download/download_default.py
+++ b/invokeai/app/services/download/download_default.py
@@ -433,11 +433,14 @@ def _do_download(self, job: DownloadJob) -> None:
         )
         if resp.status_code == 416 and resume_from > 0:
             # Range not satisfiable - local partial is already complete
-            expected = job.expected_total_bytes or job.total_bytes or resume_from
-            if resume_from == expected:
+            match = re.fullmatch(r"bytes \*/(\d+)", resp.headers.get("Content-Range", ""), flags=re.IGNORECASE)
+            expected = int(match.group(1)) if match else None
+            if expected is not None and resume_from == expected:
                 job.total_bytes = expected
+                job.expected_total_bytes = expected
                 job.bytes = resume_from
                 job.download_path = job.download_path or job.dest
+                self._in_progress_path(job.download_path).rename(job.download_path)
                 self._signal_job_started(job)
                 self._signal_job_complete(job)
                 return
diff --git a/tests/app/services/download/test_download_queue.py b/tests/app/services/download/test_download_queue.py
index bfd2e00fdbb..90e2ba1e3df 100644
--- a/tests/app/services/download/test_download_queue.py
+++ b/tests/app/services/download/test_download_queue.py
@@ -9,7 +9,7 @@
 import pytest
 from pydantic.networks import AnyHttpUrl
 from requests.sessions import Session
-from requests_testadapter import TestAdapter
+from requests_testadapter import TestAdapter, TestSession
 
 from invokeai.app.services.config import get_config
 from invokeai.app.services.config.config_default import URLRegexTokenPair
@@ -81,6 +81,64 @@ def test_errors(tmp_path: Path, mm2_session: Session) -> None:
     queue.stop()
 
 
+@pytest.mark.timeout(timeout=10, method="thread")
+def test_completed_resume_with_416_promotes_in_progress_file(tmp_path: Path) -> None:
+    source = AnyHttpUrl("https://test.com/complete.safetensors")
+    content = b"complete"
+    destination = tmp_path / "complete.safetensors"
+    in_progress_path = destination.with_name(destination.name + ".downloading")
+    in_progress_path.write_bytes(content)
+
+    session = TestSession()
+    session.mount(
+        str(source),
+        TestAdapter(b"", status=416, headers={"Content-Range": f"bytes */{len(content)}"}),
+    )
+    completed_files: list[bool] = []
+    queue = DownloadQueueService(requests_session=session)
+    queue.start()
+    try:
+        job = queue.download(
+            source=source,
+            dest=destination,
+            on_complete=lambda completed_job: completed_files.append(completed_job.download_path.exists()),
+        )
+        queue.join()
+    finally:
+        queue.stop()
+
+    assert job.status == DownloadJobStatus.COMPLETED
+    assert destination.read_bytes() == content
+    assert not in_progress_path.exists()
+    assert completed_files == [True]
+
+
+@pytest.mark.timeout(timeout=10, method="thread")
+def test_mismatched_416_resume_keeps_in_progress_file(tmp_path: Path) -> None:
+    source = AnyHttpUrl("https://test.com/stale.safetensors")
+    destination = tmp_path / "stale.safetensors"
+    in_progress_path = destination.with_name(destination.name + ".downloading")
+    in_progress_path.write_bytes(b"stale data")
+
+    session = TestSession()
+    session.mount(
+        str(source),
+        TestAdapter(b"", status=416, headers={"Content-Range": "bytes */8"}),
+    )
+    queue = DownloadQueueService(requests_session=session)
+    queue.start()
+    try:
+        job = queue.download(source=source, dest=destination)
+        queue.join()
+    finally:
+        queue.stop()
+
+    assert job.status == DownloadJobStatus.PAUSED
+    assert job.resume_required
+    assert not destination.exists()
+    assert in_progress_path.exists()
+
+
 @pytest.mark.timeout(timeout=10, method="thread")
 def test_event_bus(tmp_path: Path, mm2_session: Session) -> None:
     event_bus = TestEventService()