diff --git a/tests/pos/i14278.scala b/tests/pos/i14278.scala
new file mode 100644
index 000000000000..ebc9376fbad5
--- /dev/null
+++ b/tests/pos/i14278.scala
@@ -0,0 +1,6 @@
+// https://github.com/lampepfl/dotty/issues/14278
+class Foo
+
+extension (foo: Foo)
+  def patch(arg: List[Int], arg2: Int = 0): Unit = {}
+  def patch(arg: Int): Unit = patch(List(arg))