diff --git a/tests/test-runner/bin/zts-report.py.in b/tests/test-runner/bin/zts-report.py.in
index 1177e80e1a..6db10b91de 100755
--- a/tests/test-runner/bin/zts-report.py.in
+++ b/tests/test-runner/bin/zts-report.py.in
@@ -389,7 +389,7 @@ if os.environ.get('CI') == 'true':
 
 def process_results(pathname):
     try:
-        f = open(pathname)
+        f = open(pathname, errors='replace')
     except IOError as e:
         print('Error opening file:', e)
         sys.exit(1)