diff --git a/vm.c b/vm.c
index a8822239cf..c9f688e884 100644
--- a/vm.c
+++ b/vm.c
@@ -233,13 +233,9 @@ vm_cref_new0(VALUE klass, rb_method_visibility_t visi, int module_func, rb_cref_
     int omod_shared = FALSE;
 
     /* scope */
-    union {
-        rb_scope_visibility_t visi;
-        VALUE value;
-    } scope_visi;
-
-    scope_visi.visi.method_visi = visi;
-    scope_visi.visi.module_func = module_func;
+    rb_scope_visibility_t scope_visi;
+    scope_visi.method_visi = visi;
+    scope_visi.module_func = module_func;
 
     /* refinements */
     if (prev_cref != NULL && prev_cref != (void *)1 /* TODO: why CREF_NEXT(cref) is 1? */) {
@@ -256,7 +252,7 @@ vm_cref_new0(VALUE klass, rb_method_visibility_t visi, int module_func, rb_cref_
     rb_cref_t *cref = IMEMO_NEW(rb_cref_t, imemo_cref, refinements);
     cref->klass_or_self = klass;
     cref->next = use_prev_prev ? CREF_NEXT(prev_cref) : prev_cref;
-    *((rb_scope_visibility_t *)&cref->scope_visi) = scope_visi.visi;
+    *((rb_scope_visibility_t *)&cref->scope_visi) = scope_visi;
 
     if (pushed_by_eval) CREF_PUSHED_BY_EVAL_SET(cref);
     if (omod_shared) CREF_OMOD_SHARED_SET(cref);