diff --git a/selfprivacy_api/backup/backuppers/restic_backupper.py b/selfprivacy_api/backup/backuppers/restic_backupper.py
index 6c3dbcc..022bda7 100644
--- a/selfprivacy_api/backup/backuppers/restic_backupper.py
+++ b/selfprivacy_api/backup/backuppers/restic_backupper.py
@@ -256,6 +256,7 @@ class ResticBackupper(AbstractBackupper):
             if "created restic repository" not in output:
                 raise ValueError("cannot init a repo: " + output)
 
+    @unlocked_repo
     def is_initted(self) -> bool:
         command = self.restic_command(
             "check",
@@ -267,9 +268,10 @@ class ResticBackupper(AbstractBackupper):
             shell=False,
             stderr=subprocess.STDOUT,
         ) as handle:
-            # communication forces to complete and for returncode to get defined
             output = handle.communicate()[0].decode("utf-8")
             if handle.returncode != 0:
+                if "unable to create lock" in output:
+                    raise ValueError("Stale lock detected: ", output)
                 return False
             return True
 
@@ -319,6 +321,7 @@ class ResticBackupper(AbstractBackupper):
         except Exception as e:
             raise ValueError("could not lock repository") from e
 
+    @unlocked_repo
     def restored_size(self, snapshot_id: str) -> int:
         """
         Size of a snapshot
diff --git a/tests/test_graphql/test_backup.py b/tests/test_graphql/test_backup.py
index b575b5b..da4da7a 100644
--- a/tests/test_graphql/test_backup.py
+++ b/tests/test_graphql/test_backup.py
@@ -776,6 +776,21 @@ def test_double_lock_unlock(backups, dummy_service):
 
 
 def test_operations_while_locked(backups, dummy_service):
+    # Stale lock prevention test
+
+    # consider making it fully at the level of backupper?
+    # because this is where prevention lives?
+    # Backups singleton is here only so that we can run this against B2, S3 and whatever
+    # But maybe it is not necessary (if restic treats them uniformly enough)
+
     Backups.provider().backupper.lock()
     snap = Backups.back_up(dummy_service)
     assert snap is not None
+
+    Backups.provider().backupper.lock()
+    # using lowlevel to make sure no caching interferes
+    assert Backups.provider().backupper.is_initted() is True
+
+    # check that no locks were left
+    Backups.provider().backupper.lock()
+    Backups.provider().backupper.unlock()