diff --git a/pytorch_lightning/trainer/logging.py b/pytorch_lightning/trainer/logging.py
index 9dfb41f12f..8a178917a3 100644
--- a/pytorch_lightning/trainer/logging.py
+++ b/pytorch_lightning/trainer/logging.py
@@ -87,7 +87,8 @@ class TrainerLoggingMixin(ABC):
             callback_metrics = self.reduce_distributed_output(callback_metrics, num_gpus)
 
         for k, v in callback_metrics.items():
-            callback_metrics[k] = v.item()
+            if isinstance(v, torch.Tensor):
+                callback_metrics[k] = v.item()
 
         # ---------------
         # EXTRACT PROGRESS BAR KEYS