diff --git a/xarray/coding/cftimeindex.py b/xarray/coding/cftimeindex.py
index e236dca3693..faf1a044505 100644
--- a/xarray/coding/cftimeindex.py
+++ b/xarray/coding/cftimeindex.py
@@ -157,7 +157,7 @@ def f(self):
 
 
 def get_date_type(self):
-    if self.data:
+    if self._data.size:
         return type(self._data[0])
     else:
         return None