diff --git a/optional/capi/ext/hash_spec.c b/optional/capi/ext/hash_spec.c
index f129f0622..69ef02d5d 100644
--- a/optional/capi/ext/hash_spec.c
+++ b/optional/capi/ext/hash_spec.c
@@ -105,9 +105,11 @@ VALUE hash_spec_rb_hash_new(VALUE self) {
   return rb_hash_new();
 }
 
+#ifdef RUBY_VERSION_IS_3_2
 VALUE hash_spec_rb_hash_new_capa(VALUE self, VALUE capacity) {
   return rb_hash_new_capa(NUM2LONG(capacity));
 }
+#endif
 
 VALUE rb_ident_hash_new(void); /* internal.h, used in ripper */
 
@@ -153,7 +155,9 @@ void Init_hash_spec(void) {
   rb_define_method(cls, "rb_hash_lookup2", hash_spec_rb_hash_lookup2, 3);
   rb_define_method(cls, "rb_hash_lookup2_default_undef", hash_spec_rb_hash_lookup2_default_undef, 2);
   rb_define_method(cls, "rb_hash_new", hash_spec_rb_hash_new, 0);
+#ifdef RUBY_VERSION_IS_3_2
   rb_define_method(cls, "rb_hash_new_capa", hash_spec_rb_hash_new_capa, 1);
+#endif
   rb_define_method(cls, "rb_ident_hash_new", hash_spec_rb_ident_hash_new, 0);
   rb_define_method(cls, "rb_hash_size", hash_spec_rb_hash_size, 1);
   rb_define_method(cls, "rb_hash_set_ifnone", hash_spec_rb_hash_set_ifnone, 2);