diff --git a/src/nvim/api/private/helpers.c b/src/nvim/api/private/helpers.c
index b8d62e42a1..cdd1f42ae1 100644
--- a/src/nvim/api/private/helpers.c
+++ b/src/nvim/api/private/helpers.c
@@ -1365,6 +1365,9 @@ Dictionary copy_dictionary(Dictionary dict)
 Object copy_object(Object obj)
 {
   switch (obj.type) {
+    case kObjectTypeBuffer:
+    case kObjectTypeTabpage:
+    case kObjectTypeWindow:
     case kObjectTypeNil:
     case kObjectTypeBoolean:
     case kObjectTypeInteger: