diff --git a/test/test_known_epitopes.py b/test/test_known_epitopes.py
index 0ee6d38..640092f 100644
--- a/test/test_known_epitopes.py
+++ b/test/test_known_epitopes.py
@@ -44,5 +44,5 @@ def test_HIV_epitope():
     for mhc_class in mhc_classes:
         mhc_model = mhc_class("HLA-A*02:01", epitope_lengths=9)
         epitope = mhc_model.predict("SLYNTVATL")[0]
-        assert epitope.percentile_rank <= 4.0, \
-            "Expected %s to have percentile rank <= 3.0" % str(epitope)
+        assert epitope.value < 500, \
+            "Expected %s to have IC50 < 500nM" % (epitope,)