diff --git a/test/numbertheory.py b/test/numbertheory.py
index d485115a..ae3ba324 100644
--- a/test/numbertheory.py
+++ b/test/numbertheory.py
@@ -177,3 +177,5 @@ class ModP(object):
         return "0x{:x}".format(self.n)
     def __repr__(self):
         return "{}(0x{:x},0x{:x})".format(type(self).__name__, self.p, self.n)
+    def __hash__(self):
+        return hash((type(self).__name__, self.p, self.n))