diff --git a/ext/openssl/extconf.rb b/ext/openssl/extconf.rb
index 6eb401cf5..afbed10b5 100644
--- a/ext/openssl/extconf.rb
+++ b/ext/openssl/extconf.rb
@@ -38,7 +38,7 @@
 
 $defs.push("-D""OPENSSL_SUPPRESS_DEPRECATED")
 
-have_func("rb_io_descriptor")
+have_func("rb_io_descriptor", "ruby/io.h")
 have_func("rb_io_maybe_wait(0, Qnil, Qnil, Qnil)", "ruby/io.h") # Ruby 3.1
 have_func("rb_io_timeout", "ruby/io.h")