diff --git a/tests/lean/simplifier1.hlean b/tests/lean/simplifier1.hlean
new file mode 100644
index 000000000..8c17fde48
--- /dev/null
+++ b/tests/lean/simplifier1.hlean
@@ -0,0 +1,27 @@
+open nat
+-- deeper congruence
+
+universe l
+constants (T : Type.{l}) (x1 x2 x3 x4 x5 x6 : T) (f : T → T → T)
+constants (f_comm : ∀ x y, f x y = f y x)
+          (f_l : ∀ x y z, f (f x y) z = f x (f y z))
+          (f_r : ∀ x y z, f x (f y z) = f y (f x z))
+
+attribute f_comm [simp]
+attribute f_l [simp]
+attribute f_r [simp]
+
+#simplify eq 0 (f (f x2 x4) (f x5 (f x3 (f x1 x6))))
+
+open is_trunc
+
+constants g : Π (x y : nat), x ≠ y → Type₁
+constants a b c : nat
+constants H₁ : a ≠ b
+constants H₂ : a = c
+attribute H₂ [simp]
+
+definition ne_is_hprop [instance] (a b : nat) : is_hprop (a ≠ b) :=
+sorry
+
+#simplify eq 0 (g a b H₁)
diff --git a/tests/lean/simplifier1.hlean.expected.out b/tests/lean/simplifier1.hlean.expected.out
new file mode 100644
index 000000000..5040023c8
--- /dev/null
+++ b/tests/lean/simplifier1.hlean.expected.out
@@ -0,0 +1,2 @@
+f x1 (f x2 (f x3 (f x4 (f x5 x6))))
+g c b (eq.nrec (eq.nrec H₁ b (eq.refl b)) c H₂)