diff --git a/python/tests/test_beagle.py b/python/tests/test_beagle.py
index 7ca2fb65ae..aeb2493e94 100644
--- a/python/tests/test_beagle.py
+++ b/python/tests/test_beagle.py
@@ -51,6 +51,7 @@ def convert_to_genetic_map_position(pos):
     :return: Genetic map positions.
     :rtype: numpy.ndarray
     """
+    assert 0 <= np.min(pos)
     return pos / 1e6