diff --git a/insns.def b/insns.def
index 91ae4563f0..d9a49356a6 100644
--- a/insns.def
+++ b/insns.def
@@ -730,12 +730,7 @@ opt_str_freeze
 ()
 (VALUE val)
 {
-    if (BASIC_OP_UNREDEFINED_P(BOP_FREEZE, STRING_REDEFINED_OP_FLAG)) {
-	val = str;
-    }
-    else {
-	val = rb_funcall(rb_str_resurrect(str), idFreeze, 0);
-    }
+    val = vm_opt_str_freeze(str, BOP_FREEZE, idFreeze);
 }
 
 DEFINE_INSN
@@ -744,12 +739,7 @@ opt_str_uminus
 ()
 (VALUE val)
 {
-    if (BASIC_OP_UNREDEFINED_P(BOP_UMINUS, STRING_REDEFINED_OP_FLAG)) {
-	val = str;
-    }
-    else {
-	val = rb_funcall(rb_str_resurrect(str), idUMinus, 0);
-    }
+    val = vm_opt_str_freeze(str, BOP_UMINUS, idUMinus);
 }
 
 DEFINE_INSN
diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index 1f22cc64be..3fac8eb1fa 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -3213,6 +3213,17 @@ vm_find_or_create_class_by_id(ID id,
     }
 }
 
+static VALUE
+vm_opt_str_freeze(VALUE str, int bop, ID id)
+{
+    if (BASIC_OP_UNREDEFINED_P(bop, STRING_REDEFINED_OP_FLAG)) {
+	return str;
+    }
+    else {
+	return rb_funcall(rb_str_resurrect(str), id, 0);
+    }
+}
+
 /* this macro is mandatory to use OPTIMIZED_CMP. What a design! */
 #define id_cmp idCmp