diff --git a/src/if_ruby.c b/src/if_ruby.c
index bf7aa1a..24814a2 100644
--- a/src/if_ruby.c
+++ b/src/if_ruby.c
@@ -506,7 +506,11 @@
 {
     return dll_rb_num2long(x);
 }
+#  if defined(DYNAMIC_RUBY_VER) && DYNAMIC_RUBY_VER >= 26
+VALUE rb_int2big_stub(intptr_t x)
+#  else
 VALUE rb_int2big_stub(SIGNED_VALUE x)
+#  endif
 {
     return dll_rb_int2big(x);
 }