diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8276edc61..86f428ec3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Added missing `weights_only=False` argument to fix loading train checkpoints with newer versions of PyTorch.
+- Fixed bug where GCS upload does not retry on transient failures. 
 
 ## [v1.7.0](https://github.com/allenai/OLMo-core/releases/tag/v1.7.0) - 2024-11-27
 
diff --git a/src/olmo_core/io.py b/src/olmo_core/io.py
index 5fda27410..dce249938 100644
--- a/src/olmo_core/io.py
+++ b/src/olmo_core/io.py
@@ -2,6 +2,7 @@
 import logging
 import os
 import pickle
+import random
 import re
 import shutil
 import time
@@ -590,11 +591,20 @@ def _gcs_upload(source: Path, bucket_name: str, key: str, save_overwrite: bool =
     storage_client = _get_gcs_client()
     bucket = storage_client.bucket(bucket_name)
     blob = bucket.blob(key)
-    if not save_overwrite and blob.exists():
-        raise FileExistsError(
-            f"gs://{bucket_name}/{key} already exists. Use save_overwrite to overwrite it."
-        )
-    blob.upload_from_filename(source, retry=_get_gcs_conditional_retry())
+
+    generation: int = 0
+    if blob.exists():
+        if not save_overwrite:
+            raise FileExistsError(
+                f"gs://{bucket_name}/{key} already exists. Use save_overwrite to overwrite it."
+            )
+
+        assert blob.generation is not None
+        generation = blob.generation
+
+    blob.upload_from_filename(
+        source, if_generation_match=generation, retry=_get_gcs_conditional_retry()
+    )
 
 
 @retriable()