1 files changed, 5 insertions, 2 deletions
diff --git a/src/main/scala/chisel3/aop/Select.scala b/src/main/scala/chisel3/aop/Select.scala
index 612cdcc7..390f82a5 100644
--- a/src/main/scala/chisel3/aop/Select.scala
+++ b/src/main/scala/chisel3/aop/Select.scala
@@ -80,8 +80,11 @@ object Select {
     */
   def instances(module: BaseModule): Seq[BaseModule] = {
     check(module)
-    module._component.get.asInstanceOf[DefModule].commands.collect {
-      case i: DefInstance => i.id
+    module._component.get match {
+      case d: DefModule => d.commands.collect {
+        case i: DefInstance => i.id
+      }
+      case other => Nil
     }
   }