diff --git a/rowers/dataprep.py b/rowers/dataprep.py
index fe8c7dec..0666a418 100644
--- a/rowers/dataprep.py
+++ b/rowers/dataprep.py
@@ -71,7 +71,10 @@ def nicepaceformat(values):
     return out
 
 def timedeltaconv(x):
-    dt = datetime.timedelta(seconds=x)
+    if not np.isnan(x):
+        dt = datetime.timedelta(seconds=x)
+    else:
+        dt = 350.
 
     return dt