diff --git a/python/tests/beagle_numba.py b/python/tests/beagle_numba.py
index c6d54f2505..63dcea8d69 100644
--- a/python/tests/beagle_numba.py
+++ b/python/tests/beagle_numba.py
@@ -100,11 +100,10 @@ def check_data(ref_h, query_h):
     :return: True if alleles in query are in reference.
     :rtype: bool
     """
-    _MISSING = -1
     m = ref_h.shape[0]
     assert m == len(query_h), "Reference and query differ in length."
     for i in range(m):
-        if query_h[i] == _MISSING:
+        if query_h[i] == tskit.MISSING_DATA:
             continue
         else:
             if query_h[i] not in ref_h[i, :]: