diff --git a/mrbgems/mruby-array-ext/src/array.c b/mrbgems/mruby-array-ext/src/array.c
index 9e666fb63..41ed3612d 100644
--- a/mrbgems/mruby-array-ext/src/array.c
+++ b/mrbgems/mruby-array-ext/src/array.c
@@ -1310,13 +1310,11 @@ ary_combination_init(mrb_state *mrb, mrb_value self)
 
   mrb_get_args(mrb, "ib", &n, &permutation);
 
-  /* prepare objects in first to avoid memory leaks caused by NoMemoryError exceptions */
-  struct RData *d = mrb_data_object_alloc(mrb, mrb->object_class, NULL, NULL);
+  struct RData *d;
+  struct mrb_combination_state *state;
+  Data_Make_Struct(mrb, mrb->object_class, struct mrb_combination_state,
+                   &mrb_combination_state_type, state, d);
 
-  struct mrb_combination_state *state = (struct mrb_combination_state*)mrb_malloc(mrb, sizeof(*state));
-  d->data = state;
-  d->type = &mrb_combination_state_type;
-  state->indices = NULL;
   state->n = n;
   state->array_size = RARRAY_LEN(self);
   state->permutation = permutation;