1 files changed, 5 insertions, 5 deletions
diff --git a/src/isodate/isoduration.py b/src/isodate/isoduration.py
index af44661..5d51441 100644
--- a/src/isodate/isoduration.py
+++ b/src/isodate/isoduration.py
@@ -136,11 +136,11 @@ def duration_isoformat(tduration, format=D_DEFAULT):
     '''
     # TODO: implement better decision for negative Durations.
     #       should be done in Duration class in consistent way with timedelta.
-    if (((isinstance(tduration, Duration)
-          and (tduration.years < 0 or tduration.months < 0
-               or tduration.tdelta < timedelta(0)))
-         or (isinstance(tduration, timedelta)
-             and (tduration < timedelta(0))))):
+    if (((isinstance(tduration, Duration) and
+          (tduration.years < 0 or tduration.months < 0 or
+           tduration.tdelta < timedelta(0))) or
+        (isinstance(tduration, timedelta) and
+         (tduration < timedelta(0))))):
         ret = '-'
     else:
         ret = ''