diff --git a/calendar/teachingdates/app.py b/calendar/teachingdates/app.py
index 924824d..bb4e012 100644
--- a/calendar/teachingdates/app.py
+++ b/calendar/teachingdates/app.py
@@ -30,29 +30,29 @@
 
     except configuration.ConfigurationError as e:
         print("{prog}: error: failed to load configuration from "
-              "'{file}'".format(prog=PROG, file=e))
+              "{file}".format(prog=PROG, file=e))
     except configuration.PaperKeyError as e:
-        print("{prog}: error: paper '{paper}' in '{file}' is missing "
+        print("{prog}: error: paper '{paper}' in {file} is missing "
               "required key '{key}'".format(prog=PROG,
                                              paper=e.parent,
                                              file=e.file,
                                              key=e.key))
     except configuration.PeriodKeyError as e:
-        print("{prog}: error: teaching period '{period}' in '{file}' is "
+        print("{prog}: error: teaching period '{period}' in {file} is "
               "missing required key '{key}'".format(prog=PROG,
                                                      period=e.parent,
                                                      file=e.file,
                                                      key=e.key))
     except configuration.PaperError as e:
         print("{prog}: error: no entry for paper '{paper}' ({period}) in "
-              "'{file}.'".format(prog=PROG,
+              "{file}.".format(prog=PROG,
                                  file=e,
                                  paper=args.paper,
                                  period=args.period))
     except configuration.PeriodError as e:
         print("{prog}: error: no entry for teaching period '{period}' in "
-              "'{file}'".format(prog=PROG, file=e, period=args.period))
+              "{file}".format(prog=PROG, file=e, period=args.period))
     except TemplateNotFound as e:
         print("{prog}: error: no template found for output style '{style}' "
-              "and output format '{format}' (expected '{file}')".format(
+              "and output format '{format}' (expected {file})".format(
                   prog=PROG, style=args.style, format=args.format, file=e))