diff --git a/idl/Collector.json5 b/idl/Collector.json5
index 491c42a..6f42b85 100644
--- a/idl/Collector.json5
+++ b/idl/Collector.json5
@@ -312,7 +312,7 @@
         "",
         "/** convenience template for move-constructible T (this is common) **/",
         "template <typename T>",
-        "void * std_copy_for(const T * src) noexcept {",
+        "T * std_copy_for(const T * src) noexcept {",
         "    void * mem = this->alloc_copy_for(src);",
         "    if (mem) {",
         "        return new (mem) T(std::move(*src));",