diff --git a/tests/test_flexindex.py b/tests/test_flexindex.py
index 517c18d..516f137 100644
--- a/tests/test_flexindex.py
+++ b/tests/test_flexindex.py
@@ -134,6 +134,10 @@ def test_faiss_ivf_retriever(self):
     def test_scann_retriever(self):
         self._test_retr(FlexIndex.scann_retriever, exact=False)
 
+    @unittest.skipIf(not pyterrier_dr.util.flatnav_available(), "flatnav not available")
+    def test_flatnav_retriever(self):
+        self._test_retr(FlexIndex.flatnav_retriever, exact=False)
+
     def test_np_retriever(self):
         self._test_retr(FlexIndex.np_retriever)