diff --git a/python/paddle/fluid/layers/loss.py b/python/paddle/fluid/layers/loss.py
index dc61aa1f4cf4cd9fe2333450cfe1066799db613a..7c83b0db24df9da23eacb69b21e6feed8be15e23 100644
--- a/python/paddle/fluid/layers/loss.py
+++ b/python/paddle/fluid/layers/loss.py
@@ -611,7 +611,7 @@ def warpctc(input,
     """
     helper = LayerHelper('warpctc', **locals())
     this_inputs = {'Logits': [input], 'Label': [label]}
-    if input_length and label_length:
+    if input_length is not None and label_length is not None:
         this_inputs['LogitsLength'] = [input_length]
         this_inputs['LabelLength'] = [label_length]