diff --git a/icepyx/core/auth.py b/icepyx/core/auth.py
index 8e263e730..c5f39a470 100644
--- a/icepyx/core/auth.py
+++ b/icepyx/core/auth.py
@@ -55,7 +55,7 @@ def __init__(self, auth=None):
         self._s3login_credentials = None
         self._s3_initial_ts = None  # timer for 1h expiration on s3 credentials
 
-    def __str__(self):
+    def __str__(self) -> str:
         if self.session:
             repr_string = "EarthdataAuth obj with session initialized"
         else: