diff --git a/printrun/pronterface.py b/printrun/pronterface.py
index 84489bc2..29e6be18 100644
--- a/printrun/pronterface.py
+++ b/printrun/pronterface.py
@@ -2559,7 +2559,7 @@ def __iter__(self):
                 import itertools
                 return itertools.chain([self.header], iter(self.f))
 
-        parser.readfp(add_header(open(configfile)), configfile)
+        parser.read_file(add_header(open(configfile)), configfile)
         return parser
 
     def set_slic3r_config(self, configfile, cat, file):