diff --git a/src/dotty/tools/dotc/core/TypeErasure.scala b/src/dotty/tools/dotc/core/TypeErasure.scala
index 108d862a9914..e4f91914bbc2 100644
--- a/src/dotty/tools/dotc/core/TypeErasure.scala
+++ b/src/dotty/tools/dotc/core/TypeErasure.scala
@@ -39,7 +39,7 @@ object TypeErasure {
     case _: ErasedValueType =>
       true
     case tp: TypeRef =>
-      tp.symbol.isClass && tp.symbol != defn.AnyClass
+      tp.symbol.isClass && tp.symbol != defn.AnyClass && tp.symbol != defn.ArrayClass
     case _: TermRef =>
       true
     case JavaArrayType(elem) =>
@@ -321,6 +321,7 @@ class TypeErasure(isJava: Boolean, semiEraseVCs: Boolean, isConstructor: Boolean
       val sym = tp.symbol
       if (!sym.isClass) this(tp.info)
       else if (semiEraseVCs && isDerivedValueClass(sym)) eraseDerivedValueClassRef(tp)
+      else if (sym == defn.ArrayClass) apply(tp.appliedTo(TypeBounds.empty)) // i966 shows that we can hit a raw Array type.
       else eraseNormalClassRef(tp)
     case tp: RefinedType =>
       val parent = tp.parent
diff --git a/src/dotty/tools/dotc/transform/Erasure.scala b/src/dotty/tools/dotc/transform/Erasure.scala
index 1b9b898f2140..3445b4c444ec 100644
--- a/src/dotty/tools/dotc/transform/Erasure.scala
+++ b/src/dotty/tools/dotc/transform/Erasure.scala
@@ -109,7 +109,11 @@ class Erasure extends Phase with DenotTransformer { thisTransformer =>
   }
 
   def assertErased(tp: Type, tree: tpd.Tree = tpd.EmptyTree)(implicit ctx: Context): Unit =
-    assert(isErasedType(tp), i"The type $tp - ${tp.toString} of class ${tp.getClass} of tree $tree : ${tree.tpe} / ${tree.getClass} is illegal after erasure, phase = ${ctx.phase}")
+    if (tp.typeSymbol == defn.ArrayClass &&
+        ctx.compilationUnit.source.file.name == "Array.scala") {} // ok
+    else
+      assert(isErasedType(tp),
+        i"The type $tp - ${tp.toString} of class ${tp.getClass} of tree $tree : ${tree.tpe} / ${tree.getClass} is illegal after erasure, phase = ${ctx.phase.prev}")
 }
 
 object Erasure extends TypeTestsCasts{
diff --git a/test/dotc/scala-collections.whitelist b/test/dotc/scala-collections.whitelist
index 328d040c15bf..2abb16c1ec20 100644
--- a/test/dotc/scala-collections.whitelist
+++ b/test/dotc/scala-collections.whitelist
@@ -184,9 +184,7 @@
 ./scala-scala/src/library/scala/collection/SeqViewLike.scala
 ./scala-scala/src/library/scala/collection/mutable/IndexedSeqView.scala
 ./scala-scala/src/library/scala/collection/immutable/StreamViewLike.scala
-
-## This class causes a crash in backend -> @darkdimius
-#./scala-scala/src/library/scala/collection/immutable/TrieIterator.scala
+./scala-scala/src/library/scala/collection/immutable/TrieIterator.scala
 
 ./scala-scala/src/library/scala/collection/immutable/HashMap.scala
 ./scala-scala/src/library/scala/collection/immutable/HashSet.scala
diff --git a/tests/pos/i966.scala b/tests/pos/i966.scala
new file mode 100644
index 000000000000..1fedc00238ff
--- /dev/null
+++ b/tests/pos/i966.scala
@@ -0,0 +1,15 @@
+package scala
+package collection
+package immutable
+
+import HashMap.{ HashTrieMap, HashMapCollision1, HashMap1 }
+import HashSet.{ HashTrieSet, HashSetCollision1, HashSet1 }
+
+object i996{
+
+  private[this] def collisionToArray[T](x: Iterable[T]): Array[Iterable[T]] = (x match {
+    case x: HashMapCollision1[_, _] => x.kvs.map(x => HashMap(x)).toArray
+    case x: HashSetCollision1[_]    => x.ks.map(x => HashSet(x)).toArray
+  }).asInstanceOf[Array[Iterable[T]]]
+
+}
diff --git a/tests/pos/i996.scala b/tests/pos/i996.scala
new file mode 100644
index 000000000000..1fedc00238ff
--- /dev/null
+++ b/tests/pos/i996.scala
@@ -0,0 +1,15 @@
+package scala
+package collection
+package immutable
+
+import HashMap.{ HashTrieMap, HashMapCollision1, HashMap1 }
+import HashSet.{ HashTrieSet, HashSetCollision1, HashSet1 }
+
+object i996{
+
+  private[this] def collisionToArray[T](x: Iterable[T]): Array[Iterable[T]] = (x match {
+    case x: HashMapCollision1[_, _] => x.kvs.map(x => HashMap(x)).toArray
+    case x: HashSetCollision1[_]    => x.ks.map(x => HashSet(x)).toArray
+  }).asInstanceOf[Array[Iterable[T]]]
+
+}