diff --git a/datasketch/lshforest.py b/datasketch/lshforest.py
index bee6f29c..5bd2aeff 100644
--- a/datasketch/lshforest.py
+++ b/datasketch/lshforest.py
@@ -112,15 +112,15 @@ def query(self, minhash, k):
             raise ValueError("k must be positive")
         if len(minhash) < self.k*self.l:
             raise ValueError("The num_perm of MinHash out of range")
-        results = set()
+        results = {}
         r = self.k
         while r > 0:
             for key in self._query(minhash, r, self.l):
-                results.add(key)
+                results[key]=''
                 if len(results) >= k:
-                    return list(results)
+                    return list(results.keys())
             r -= 1
-        return list(results)
+        return list(results.keys())
 
     def _binary_search(self, n, func):
         '''