diff --git a/src/proto/if_mzsch.pro b/src/proto/if_mzsch.pro
index 00bbf3c..26ffa77 100644
--- a/src/proto/if_mzsch.pro
+++ b/src/proto/if_mzsch.pro
@@ -1,7 +1,7 @@
 /* if_mzsch.c */
 int mzscheme_enabled(int verbose);
 void mzvim_check_threads(void);
-char *did_set_mzquantum(void);
+char *did_set_mzquantum(optset_T *args);
 void mzscheme_end(void);
 int mzscheme_main(void);
 void mzscheme_buffer_free(buf_T *buf);