diff --git a/pytorch_lightning/trainer/connectors/logger_connector/logger_connector.py b/pytorch_lightning/trainer/connectors/logger_connector/logger_connector.py
index 595a5e84bf630..89c72883fc497 100644
--- a/pytorch_lightning/trainer/connectors/logger_connector/logger_connector.py
+++ b/pytorch_lightning/trainer/connectors/logger_connector/logger_connector.py
@@ -14,7 +14,7 @@
 import os
 from copy import deepcopy
 from pprint import pprint
-from typing import Dict, Iterable, Union
+from typing import Dict, Iterable, Optional, Union
 
 import torch
 
@@ -32,7 +32,7 @@
 
 class LoggerConnector:
 
-    def __init__(self, trainer, log_gpu_memory: bool):
+    def __init__(self, trainer, log_gpu_memory: Optional[str] = None):
         self.trainer = trainer
         self.log_gpu_memory = log_gpu_memory
         self._callback_metrics = MetricsHolder()