diff --git a/tests/lean/run/eq1.lean b/tests/lean/run/eq1.lean
new file mode 100644
index 000000000..5ba3494ce
--- /dev/null
+++ b/tests/lean/run/eq1.lean
@@ -0,0 +1,16 @@
+inductive day :=
+monday, tuesday, wednesday, thursday, friday, saturday, sunday
+
+open day
+
+definition next_weekday : day → day,
+next_weekday monday    := tuesday,
+next_weekday tuesday   := wednesday,
+next_weekday wednesday := thursday,
+next_weekday thursday  := friday,
+next_weekday friday    := monday,
+next_weekday saturday  := monday,
+next_weekday sunday    := monday
+
+example : next_weekday (next_weekday monday) = wednesday :=
+rfl