diff --git a/CHANGELOG.md b/CHANGELOG.md
index 901dd0a6..8b8d64d2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@
 * Wrap `ModuleNotFoundError` for `otter` in grading image to include debugging instructions per [#907](https://github.com/ucbds-infra/otter-grader/issues/907)
 * Updated Otter Assign to disallow metadata tests for Colab notebooks per [#901](https://github.com/ucbds-infra/otter-grader/issues/901)
 * Updated Otter Assign to leave solution cell tags in student notebooks per [#893](https://github.com/ucbds-infra/otter-grader/issues/893)
+* Updated `Notebook.export` zip validation to emit a `RuntimeWarning` instead of a `RuntimeError` when anything is written to stderr per [#915](https://github.com/ucbds-infra/otter-grader/issues/915)
 
 **v6.0.5:**
 
diff --git a/otter/check/utils.py b/otter/check/utils.py
index da6d59a6..53f16a91 100644
--- a/otter/check/utils.py
+++ b/otter/check/utils.py
@@ -6,6 +6,7 @@
 import sys
 import tempfile
 import time
+import warnings
 import wrapt
 
 from dataclasses import dataclass
@@ -111,7 +112,7 @@ def grade_zip_file(zip_path: str, nb_arcname: str, tests_dir: str) -> GradingRes
         print(results.stdout.decode("utf-8"))
 
         if results.stderr:
-            raise RuntimeError(results.stderr.decode("utf-8"))
+            warnings.warn(results.stderr.decode("utf-8"), RuntimeWarning)
 
         with open(results_path, "rb") as f:
             results = dill.load(f)
diff --git a/otter/check/validate_export/__main__.py b/otter/check/validate_export/__main__.py
index eb9616ea..338807ca 100644
--- a/otter/check/validate_export/__main__.py
+++ b/otter/check/validate_export/__main__.py
@@ -1,12 +1,13 @@
 """A Python module for validating that a submission zip file passes test cases"""
 
-# suppress all warnings, because otherwise they get printed to stderr which triggers a RuntimeError
-# in the calling code -- see #735
 import warnings
 
 
+# suppress all warnings, because otherwise they get printed to stderr which triggers a RuntimeError
+# in the calling code -- see #735
 warnings.simplefilter("ignore")
 
+
 import argparse
 import dill
 import os
@@ -28,11 +29,7 @@ def get_parser():
     return parser
 
 
-warnings.warn("foo", RuntimeWarning)
-
-
 def main():
-
     args = get_parser().parse_args()
 
     nb_dir = tempfile.mkdtemp()