diff --git a/cryosparc/dataset.py b/cryosparc/dataset.py
index a07c1d47..01dcdc09 100644
--- a/cryosparc/dataset.py
+++ b/cryosparc/dataset.py
@@ -645,7 +645,7 @@ def _load_numpy(
             if mmap_mode and offset < size:
                 # reset mmap to avoid excessive memory usage
                 del indata
-                indata = n.load(file, mmap_mode=mmap_mode, allow_pickle=False)
+                indata = n.load(f, mmap_mode=mmap_mode, allow_pickle=False)
 
         if cstrs:
             dset.to_cstrs()