diff --git a/compiler/src/dotty/tools/dotc/transform/ExplicitOuter.scala b/compiler/src/dotty/tools/dotc/transform/ExplicitOuter.scala
index 1eb12e9dea77..c2aacf826380 100644
--- a/compiler/src/dotty/tools/dotc/transform/ExplicitOuter.scala
+++ b/compiler/src/dotty/tools/dotc/transform/ExplicitOuter.scala
@@ -276,7 +276,8 @@ object ExplicitOuter {
           if (tpe.prefix eq NoPrefix) cls.owner.enclosingClass.thisType
           else tpe.prefix
         case _ =>
-          outerPrefix(tpe.underlying)
+          // Need to be careful to dealias before erasure, otherwise we lose prefixes.
+          outerPrefix(tpe.underlying(ctx.withPhaseNoLater(ctx.erasurePhase)))
       }
     case tpe: TypeProxy =>
       outerPrefix(tpe.underlying)
diff --git a/tests/pos/i1865.scala b/tests/pos/i1865.scala
new file mode 100644
index 000000000000..1b77558ff450
--- /dev/null
+++ b/tests/pos/i1865.scala
@@ -0,0 +1,24 @@
+class AbsCell {
+  type T = Node
+  class Node
+}
+
+object Test {
+  def test: Unit = {
+    val cell = new AbsCell
+    new cell.T
+  }
+}
+
+class AbsCell2 {
+  type T = Node
+  val value: T = value
+  def set(x: T): Unit = {}
+  class Node
+}
+object init {
+  def main = {
+    val cell = new AbsCell2 { val init = new Node }
+    cell set (new cell.T)
+  }
+}