diff --git a/pytorch_lightning/models/trainer.py b/pytorch_lightning/models/trainer.py
index 74875e36..9b477442 100644
--- a/pytorch_lightning/models/trainer.py
+++ b/pytorch_lightning/models/trainer.py
@@ -201,6 +201,7 @@ class Trainer(TrainerIO):
                 output = reduce_distributed_output(output, len(self.data_parallel_device_ids))
             else:
                 output = model.validation_step(data_batch, batch_i)
+                pdb.set_trace()
                 output = reduce_distributed_output(output, 1)
 
             outputs.append(output)