diff --git a/src/flatland/ordered/set.clj b/src/flatland/ordered/set.clj
index 21c424c..0257069 100644
--- a/src/flatland/ordered/set.clj
+++ b/src/flatland/ordered/set.clj
@@ -56,7 +56,7 @@
   (toString [this]
     (str "#{" (clojure.string/join " " (map str this)) "}"))
   (hashCode [this]
-    (reduce + (keep #(when % (.hashCode ^Object %)) (.seq this))))
+    (reduce + (keep #(when (some? %) (.hashCode ^Object %)) (.seq this))))
   (equals [this other]
     (or (identical? this other)
         (and (instance? Set other)
diff --git a/test/flatland/ordered/set_test.clj b/test/flatland/ordered/set_test.clj
index ddae56c..c2fa070 100644
--- a/test/flatland/ordered/set_test.clj
+++ b/test/flatland/ordered/set_test.clj
@@ -165,6 +165,11 @@
     (is (= (.hashCode (ordered-set nil)) (.hashCode (hash-set nil))))
     (is (= (.hashCode (ordered-set nil :a {:b nil})) (.hashCode (hash-set nil :a {:b nil}))))))
 
+(deftest nil-and-false-hashes
+  (is (not= (.hashCode (ordered-set nil)) (.hashCode (hash-set false))))
+  (is (not= (.hashCode (ordered-set false)) (.hashCode (hash-set nil))))
+  (is (= (.hashCode (ordered-set false nil)) (.hashCode (hash-set nil false)))))
+
 (deftest nil-hash-code-npe
   ;; No assertions here; just check that it doesn't NPE
   ;; See: https://github.com/amalloy/ordered/issues/27