diff --git a/python/tests/beagle_numba.py b/python/tests/beagle_numba.py
index 1f4c0b84be..5150680c61 100644
--- a/python/tests/beagle_numba.py
+++ b/python/tests/beagle_numba.py
@@ -136,8 +136,9 @@ def get_mismatch_prob(pos, error_rate):
     :return: Mismatch probabilities.
     :rtype: numpy.ndarray
     """
-    if error_rate >= 0.5:
-        error_rate = 0.5
+    MAX_ERROR_RATE = 0.5
+    if error_rate >= MAX_ERROR_RATE:
+        error_rate = MAX_ERROR_RATE
     mu = np.zeros(len(pos), dtype=np.float32) + error_rate
     return mu