diff --git a/src/runtime/object.cpp b/src/runtime/object.cpp
index e2878c57a1..0fcf649cb8 100644
--- a/src/runtime/object.cpp
+++ b/src/runtime/object.cpp
@@ -2064,11 +2064,17 @@ extern "C" LEAN_EXPORT obj_res lean_copy_expand_array(obj_arg a, bool expand) {
     object ** it   = lean_array_cptr(a);
     object ** end  = it + sz;
     object ** dest = lean_array_cptr(r);
-    for (; it != end; ++it, ++dest) {
-        *dest = *it;
-        lean_inc(*it);
+    if (lean_is_exclusive(a)) {
+        // transfer ownership of elements directly instead of inc+dec
+        memcpy(dest, it, sz * sizeof(object *));
+        lean_dealloc(a, lean_array_byte_size(a));
+    } else {
+        for (; it != end; ++it, ++dest) {
+            *dest = *it;
+            lean_inc(*it);
+        }
+        lean_dec(a);
     }
-    lean_dec(a);
     return r;
 }