diff --git a/compiler/src/dotty/tools/dotc/core/TypeComparer.scala b/compiler/src/dotty/tools/dotc/core/TypeComparer.scala
index 3b2cb0db78c3..159102e1f875 100644
--- a/compiler/src/dotty/tools/dotc/core/TypeComparer.scala
+++ b/compiler/src/dotty/tools/dotc/core/TypeComparer.scala
@@ -912,7 +912,7 @@ class TypeComparer(@constructorOnly initctx: Context) extends ConstraintHandling
                 // scala.AnyRef [Scala 3: which scala.Null conforms to], the type denotes the set of values consisting
                 // of null and the value denoted by p (i.e., the value v for which v eq p). [Otherwise,] the type
                 // denotes the set consisting of only the value denoted by p.
-                isNullable(tp.underlying) && tp.isStable
+                !ctx.explicitNulls && isNullable(tp.underlying) && tp.isStable
               case tp: RefinedOrRecType => isNullable(tp.parent)
               case tp: AppliedType => isNullable(tp.tycon)
               case AndType(tp1, tp2) => isNullable(tp1) && isNullable(tp2)
diff --git a/tests/explicit-nulls/neg/i17467.scala b/tests/explicit-nulls/neg/i17467.scala
new file mode 100644
index 000000000000..b9220c8fece1
--- /dev/null
+++ b/tests/explicit-nulls/neg/i17467.scala
@@ -0,0 +1,10 @@
+object Test:
+  def test(): Unit =
+    val a1: String = "foo"
+    val a2: a1.type = null // error
+
+    val b1: String | Null = "foo"
+    val b2: b1.type = null // error
+    summon[Null, b1.type] // error
+  end test
+end Test