diff --git a/tests/test_backup.py b/tests/test_backup.py
index 6374abafa286a306963e0f0de1a128b3c2ca01be..f44dda19c645445c428af6cc3d91197d2d54e728 100755
--- a/tests/test_backup.py
+++ b/tests/test_backup.py
@@ -85,7 +85,7 @@ def check_backup_is_incremental(path):
 
     for d in dirs:
         num_folders = 0
-        if os.path.isdir(d):
+        if os.path.isdir(os.path.join(path, d)):
             media = glob.glob(os.path.join(path, d, "*/msinstance/media/resources/"))
             for m in media:
                 num_folders += len(os.listdir(m))