diff --git a/tests/pos/i11631.scala b/tests/pos/i11631.scala
new file mode 100644
index 000000000000..96cd46578d76
--- /dev/null
+++ b/tests/pos/i11631.scala
@@ -0,0 +1,19 @@
+trait MyTrait:
+  def a(): String = ""
+
+class Nul
+
+extension [T](x: T | Nul) inline def nnn: x.type & T = ???
+
+class MyClass:
+  var myTrait: MyTrait|Null = null
+
+  def printA(): Unit = println(myTrait.nnn.a())
+
+@main def runTest(): Unit =
+  val mt = new MyTrait:
+    override def a(): String = "hello world"
+
+  val mc = MyClass()
+  mc.myTrait = mt
+  mc.printA()
diff --git a/tests/pos/i11631b.scala b/tests/pos/i11631b.scala
new file mode 100644
index 000000000000..6f91532158fe
--- /dev/null
+++ b/tests/pos/i11631b.scala
@@ -0,0 +1,15 @@
+trait MyTrait:
+  def a(): String = ""
+
+class MyClass:
+  var myTrait: MyTrait|Null = null
+
+  def printA(): Unit = println(myTrait.nn.a())
+
+@main def runTest(): Unit =
+  val mt = new MyTrait:
+    override def a(): String = "hello world"
+
+  val mc = MyClass()
+  mc.myTrait = mt
+  mc.printA()