diff --git a/src/if_ruby.c b/src/if_ruby.c
index 3b5b93b..ab4ac69 100644
--- a/src/if_ruby.c
+++ b/src/if_ruby.c
@@ -1238,7 +1238,7 @@
     return Qnil;
 }
 
-static VALUE f_nop(VALUE self)
+static VALUE f_nop(VALUE self UNUSED)
 {
     return Qnil;
 }