diff --git a/pytorch_lightning/core/lightning.py b/pytorch_lightning/core/lightning.py
index a34a5a93..04a386d7 100644
--- a/pytorch_lightning/core/lightning.py
+++ b/pytorch_lightning/core/lightning.py
@@ -539,7 +539,7 @@ class LightningModule(ABC, GradInformation, ModelIO, ModelHooks):
             # the pseudocode for these calls
             val_outs = []
             for val_batch in val_data:
-                out = validation_step(train_batch)
+                out = validation_step(val_batch)
                 val_outs.append(out)
             validation_epoch_end(val_outs)