diff --git a/src/omero/cli.py b/src/omero/cli.py
index ad7060201..927aa92de 100755
--- a/src/omero/cli.py
+++ b/src/omero/cli.py
@@ -1118,7 +1118,7 @@ def _exists(self, p):
                              r'error:?\s')
                 warn = 0
                 err = 0
-                for l in p.lines():
+                for l in p.lines(errors="surrogateescape"):
                     # ensure errors/warnings search is case-insensitive
                     lcl = l.lower()
                     if re.match(warn_regex, lcl):