diff --git a/dwave/cloud/solver.py b/dwave/cloud/solver.py
index 955c4bd9..e0638862 100644
--- a/dwave/cloud/solver.py
+++ b/dwave/cloud/solver.py
@@ -206,7 +206,7 @@ def check_problem(self, linear, quadratic):
                 return False
         return True
 
-    def retrieve_problem(self, id_):
+    def _retrieve_problem(self, id_):
         """Resume polling for a problem previously submitted.
 
         Args:
diff --git a/tests/test_mock_submission.py b/tests/test_mock_submission.py
index 9e46d140..151ad09f 100644
--- a/tests/test_mock_submission.py
+++ b/tests/test_mock_submission.py
@@ -339,8 +339,8 @@ def continue_then_complete(path, state={'count': 0}):
             future = solver.sample_qubo({})
             future.result()
 
-            # after third poll, back-off interval should be 4
-            self.assertEqual(future._poll_backoff, 4)
+            # after third poll, back-off interval should be 4 x initial back-off
+            self.assertEqual(future._poll_backoff, Client._POLL_BACKOFF_MIN * 2**2)
 
     @mock.patch.object(Client, "_POLL_THREAD_COUNT", 1)
     @mock.patch.object(Client, "_SUBMISSION_THREAD_COUNT", 1)
@@ -425,7 +425,7 @@ def test_cancel_with_id(self):
             client.session.delete = DeleteEvent.handle
 
             solver = Solver(client, solver_data('abc123'))
-            future = solver.retrieve_problem(submission_id)
+            future = solver._retrieve_problem(submission_id)
             future.cancel()
 
             try: