diff --git a/src/nvim/api/private/helpers.c b/src/nvim/api/private/helpers.c
index 2056cb07e3..d915ac9db5 100644
--- a/src/nvim/api/private/helpers.c
+++ b/src/nvim/api/private/helpers.c
@@ -1363,6 +1363,9 @@ 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: