diff --git a/test/clojure/core_test/fnil.cljc b/test/clojure/core_test/fnil.cljc
new file mode 100644
index 0000000..57c8dc6
--- /dev/null
+++ b/test/clojure/core_test/fnil.cljc
@@ -0,0 +1,31 @@
+(ns clojure.core-test.fnil
+  (:require [clojure.test :as t]))
+
+(defn test-fn [& x]
+  (into [] x))
+
+(def arg 'not-nil)
+
+(t/deftest fnil-test
+  (let [arity-1 (fnil test-fn 100)]
+    (t/is (= [100]             (arity-1 nil)))
+    (t/is (= [arg]             (arity-1 arg))))
+  (let [arity-2 (fnil test-fn 100 200)]
+    (t/is (= [100 200]         (arity-2 nil nil)))
+    (t/is (= [arg 200]         (arity-2 arg nil)))
+    (t/is (= [100 arg]         (arity-2 nil arg)))
+    (t/is (= [arg arg]         (arity-2 arg arg))))
+  (let [arity-3 (fnil test-fn 100 200 300)]
+    (t/is (= [100 200 300]     (arity-3 nil nil nil)))
+    (t/is (= [arg 200 300]     (arity-3 arg nil nil)))
+    (t/is (= [100 arg 300]     (arity-3 nil arg nil)))
+    (t/is (= [100 200 arg]     (arity-3 nil nil arg)))
+    (t/is (= [arg arg 300]     (arity-3 arg arg nil)))
+    (t/is (= [100 arg arg]     (arity-3 nil arg arg)))
+    (t/is (= [arg 200 arg]     (arity-3 arg nil arg)))
+    (t/is (= [arg arg arg]     (arity-3 arg arg arg))))
+  (let [arity-+ (fnil test-fn 100 200 300)]
+    (t/is (= [100 200 300 arg] (arity-+ nil nil nil arg)))
+    (t/is (= [arg 200 300 arg] (arity-+ arg nil nil arg)))
+    (t/is (= [100 arg 300 arg] (arity-+ nil arg nil arg)))
+    (t/is (= [100 200 arg arg] (arity-+ nil nil arg arg)))))