diff --git a/src/clusterfuzz/_internal/bot/tasks/utasks/fuzz_task.py b/src/clusterfuzz/_internal/bot/tasks/utasks/fuzz_task.py
index 610e2de014..3e5d4e5c5f 100644
--- a/src/clusterfuzz/_internal/bot/tasks/utasks/fuzz_task.py
+++ b/src/clusterfuzz/_internal/bot/tasks/utasks/fuzz_task.py
@@ -2044,7 +2044,8 @@ def _to_engine_output(output: str, return_code: int,
 
 def _upload_engine_output_log(engine_output):
   timestamp = uworker_io.proto_timestamp_to_timestamp(engine_output.timestamp)
-  testcase_manager.upload_log(engine_output.output, engine_output.return_code,
+  testcase_manager.upload_log(engine_output.output.decode(),
+                              engine_output.return_code,
                               timestamp)