diff --git a/array.c b/array.c
index a32aad7811..915cb566d1 100644
--- a/array.c
+++ b/array.c
@@ -3759,7 +3759,7 @@ rb_ary_equal(VALUE ary1, VALUE ary2)
 {
     if (ary1 == ary2) return Qtrue;
     if (!RB_TYPE_P(ary2, T_ARRAY)) {
-	if (!rb_respond_to(ary2, rb_intern("to_ary"))) {
+	if (!rb_respond_to(ary2, idTo_ary)) {
 	    return Qfalse;
 	}
 	return rb_equal(ary2, ary1);
diff --git a/hash.c b/hash.c
index 61f64101d3..93efde762a 100644
--- a/hash.c
+++ b/hash.c
@@ -1930,7 +1930,7 @@ hash_equal(VALUE hash1, VALUE hash2, int eql)
 
     if (hash1 == hash2) return Qtrue;
     if (!RB_TYPE_P(hash2, T_HASH)) {
-	if (!rb_respond_to(hash2, rb_intern("to_hash"))) {
+	if (!rb_respond_to(hash2, idTo_hash)) {
 	    return Qfalse;
 	}
 	if (eql)