diff --git a/testgres/node.py b/testgres/node.py
index 84c25327..52e6d2ee 100644
--- a/testgres/node.py
+++ b/testgres/node.py
@@ -659,7 +659,7 @@ def get_control_data(self):
 
         return out_dict
 
-    def slow_start(self, replica=False, dbname='template1', username=default_username(), max_attempts=0):
+    def slow_start(self, replica=False, dbname='template1', username=None, max_attempts=0):
         """
         Starts the PostgreSQL instance and then polls the instance
         until it reaches the expected state (primary or replica). The state is checked
@@ -672,6 +672,8 @@ def slow_start(self, replica=False, dbname='template1', username=default_usernam
                         If False, waits for the instance to be in primary mode. Default is False.
                max_attempts:
         """
+        if not username:
+            username = default_username()
         self.start()
 
         if replica:
diff --git a/testgres/operations/local_ops.py b/testgres/operations/local_ops.py
index a692750e..36b14058 100644
--- a/testgres/operations/local_ops.py
+++ b/testgres/operations/local_ops.py
@@ -117,7 +117,7 @@ def set_env(self, var_name, var_val):
 
     # Get environment variables
     def get_user(self):
-        return getpass.getuser()
+        return self.username or getpass.getuser()
 
     def get_name(self):
         return os.name