diff --git a/letsencrypt/auth_handler.py b/letsencrypt/auth_handler.py
index e77f83248..c63d8c8d4 100644
--- a/letsencrypt/auth_handler.py
+++ b/letsencrypt/auth_handler.py
@@ -540,11 +540,11 @@ def _generate_failed_chall_msg(failed_achalls):
 
     """
     typ = failed_achalls[0].error.typ
-    msg = [
-        "The following errors were reported by the server:".format(typ)]
+    msg = ["The following errors were reported by the server:"]
 
     for achall in failed_achalls:
-        msg.append("\n\nDomain: %s\nType:   %s\nDetail: %s" % (achall.domain, achall.error.typ, achall.error.detail))
+        msg.append("\n\nDomain: %s\nType:   %s\nDetail: %s" % (
+            achall.domain, achall.error.typ, achall.error.detail))
 
     if typ in _ERROR_HELP:
         msg.append("\n\n")