diff --git a/src/xfel_calibrate/calibrate.py b/src/xfel_calibrate/calibrate.py
index ebc1a54cd2dec6c859d949f530cf739447607a64..90dd3c4b530d0886137b03c830f4944528ba383a 100755
--- a/src/xfel_calibrate/calibrate.py
+++ b/src/xfel_calibrate/calibrate.py
@@ -583,10 +583,6 @@ def make_par_table(parms):
 
 def run(argv=None):
     """ Run a calibration task with parser arguments """
-    # Ensure files are opened as UTF-8 by default, regardless of environment.
-    if "readthedocs.org" not in sys.executable:
-        locale.setlocale(locale.LC_CTYPE, ('C', 'UTF-8'))
-
     if argv is None:
         argv = sys.argv