diff --git a/qlib/utils/__init__.py b/qlib/utils/__init__.py
index d0b47d3cd..900d9e115 100644
--- a/qlib/utils/__init__.py
+++ b/qlib/utils/__init__.py
@@ -44,7 +44,7 @@ def read_bin(file_path, start_index, end_index):
         ref_start_index = int(np.frombuffer(f.read(4), dtype="<f")[0])
         si = max(ref_start_index, start_index)
         if si > end_index:
-            return pd.Series(np.float32)
+            return pd.Series(dtype=np.float32)
         # calculate offset
         f.seek(4 * (si - ref_start_index) + 4)
         # read nbytes