diff --git a/imap_processing/idex/l1/idex_l1.py b/imap_processing/idex/l1/idex_l1.py
index cde3f1a40..d664b66ee 100644
--- a/imap_processing/idex/l1/idex_l1.py
+++ b/imap_processing/idex/l1/idex_l1.py
@@ -9,6 +9,7 @@
 from enum import IntEnum
 
 import numpy as np
+import numpy.typing as npt
 import space_packet_parser
 import xarray as xr
 
@@ -421,7 +422,7 @@ def _parse_low_sample_waveform(self, waveform_raw: str) -> list[int]:
             ]
         return ints
 
-    def _calc_low_sample_resolution(self, num_samples: int) -> np.ndarray:
+    def _calc_low_sample_resolution(self, num_samples: int) -> npt.NDArray:
         """
         Calculate the resolution of the low samples.
 
@@ -447,7 +448,7 @@ def _calc_low_sample_resolution(self, num_samples: int) -> np.ndarray:
         )
         return time_low_sr_data
 
-    def _calc_high_sample_resolution(self, num_samples: int) -> np.ndarray:
+    def _calc_high_sample_resolution(self, num_samples: int) -> npt.NDArray:
         """
         Calculate the resolution of high samples.