diff --git a/src/if_ruby.c b/src/if_ruby.c
index 8dd6064..74de2f0 100644
--- a/src/if_ruby.c
+++ b/src/if_ruby.c
@@ -789,7 +789,7 @@
     return get_buffer_line(curbuf, curwin->w_cursor.lnum);
 }
 
-static VALUE set_current_line(VALUE str)
+static VALUE set_current_line(VALUE self, VALUE str)
 {
     return set_buffer_line(curbuf, curwin->w_cursor.lnum, str);
 }