diff --git a/src/treq/client.py b/src/treq/client.py
index 9095680b..509160b0 100644
--- a/src/treq/client.py
+++ b/src/treq/client.py
@@ -400,9 +400,10 @@ def _convert_files(files):
                 # TypeError about being unable to coerce None.
                 raise TypeError(
                     (
-                        "`files` argument must be a sequence of tuples of (file_name, file_obj)"
-                        " or (file_name, content_type, file_obj), but the {!r} tuple"
-                        " has length {}: {!r}"
+                        "`files` argument must be a sequence of tuples of"
+                        " (file_name, file_obj) or"
+                        " (file_name, content_type, file_obj),"
+                        " but the {!r} tuple has length {}: {!r}"
                     ).format(param, len(val), val),
                 )
         else: