diff --git a/infra/base-images/base-runner/test_one.py b/infra/base-images/base-runner/test_one.py
index 9bdb75faf..e391ec96d 100755
--- a/infra/base-images/base-runner/test_one.py
+++ b/infra/base-images/base-runner/test_one.py
@@ -25,7 +25,11 @@ def test_one(fuzz_target):
   """Does bad_build_check on one fuzz target. Returns True on success."""
   with test_all.use_different_out_dir():
     fuzz_target_path = os.path.join(os.environ['OUT'], fuzz_target)
-    return test_all.do_bad_build_check(fuzz_target_path).returncode == 0
+    result = test_all.do_bad_build_check(fuzz_target_path)
+    if result.returncode != 0:
+      sys.stdout.buffer.write(result.stdout + result.stderr + b'\n')
+      return False
+    return True
 
 
 def main():