diff --git a/test/tribool_test.cpp b/test/tribool_test.cpp
index 85d6b68..f14a8c5 100644
--- a/test/tribool_test.cpp
+++ b/test/tribool_test.cpp
@@ -75,7 +75,7 @@ int main()
   assert(!(x && z));
   assert((y && z) == indeterminate);
   assert((z && z) == indeterminate);
-  assert((z || z) == indeterminate);
+  assert(indeterminate(z || z));
   assert(x || z == indeterminate);
   assert(y || z);