diff --git a/src/proto/gui_xim.pro b/src/proto/gui_xim.pro
index 8c5c53a..2e944ae 100644
--- a/src/proto/gui_xim.pro
+++ b/src/proto/gui_xim.pro
@@ -1,6 +1,6 @@
 /* gui_xim.c */
-int set_imactivatefunc_option(void);
-int set_imstatusfunc_option(void);
+char *set_imactivatefunc_option(void);
+char *set_imstatusfunc_option(void);
 void free_xim_stuff(void);
 int set_ref_in_im_funcs(int copyID);
 void im_set_active(int active);
diff --git a/src/proto/insexpand.pro b/src/proto/insexpand.pro
index c9183bb..b10d2a8 100644
--- a/src/proto/insexpand.pro
+++ b/src/proto/insexpand.pro
@@ -44,11 +44,11 @@
 void ins_compl_addleader(int c);
 void ins_compl_addfrommatch(void);
 int ins_compl_prep(int c);
-int set_completefunc_option(void);
+char *set_completefunc_option(void);
 void set_buflocal_cfu_callback(buf_T *buf);
-int set_omnifunc_option(void);
+char *set_omnifunc_option(void);
 void set_buflocal_ofu_callback(buf_T *buf);
-int set_thesaurusfunc_option(void);
+char *set_thesaurusfunc_option(void);
 int set_ref_in_insexpand_funcs(int copyID);
 void f_complete(typval_T *argvars, typval_T *rettv);
 void f_complete_add(typval_T *argvars, typval_T *rettv);
diff --git a/src/proto/ops.pro b/src/proto/ops.pro
index 1e89c4e..8a25bf6 100644
--- a/src/proto/ops.pro
+++ b/src/proto/ops.pro
@@ -17,7 +17,7 @@
 void op_addsub(oparg_T *oap, linenr_T Prenum1, int g_cmd);
 void clear_oparg(oparg_T *oap);
 void cursor_pos_info(dict_T *dict);
-int set_operatorfunc_option(void);
+char *set_operatorfunc_option(void);
 void free_operatorfunc_option(void);
 int set_ref_in_opfunc(int copyID);
 void do_pending_operator(cmdarg_T *cap, int old_col, int gui_yank);
diff --git a/src/proto/quickfix.pro b/src/proto/quickfix.pro
index 913c3c4..3a210b0 100644
--- a/src/proto/quickfix.pro
+++ b/src/proto/quickfix.pro
@@ -15,7 +15,7 @@
 void ex_copen(exarg_T *eap);
 void ex_cbottom(exarg_T *eap);
 linenr_T qf_current_entry(win_T *wp);
-int qf_process_qftf_option(void);
+char *qf_process_qftf_option(void);
 int grep_internal(cmdidx_T cmdidx);
 void ex_make(exarg_T *eap);
 int qf_get_size(exarg_T *eap);
diff --git a/src/proto/tag.pro b/src/proto/tag.pro
index 9820571..f42e3f8 100644
--- a/src/proto/tag.pro
+++ b/src/proto/tag.pro
@@ -1,5 +1,5 @@
 /* tag.c */
-int set_tagfunc_option(void);
+char *set_tagfunc_option(void);
 void free_tagfunc_option(void);
 int set_ref_in_tagfunc(int copyID);
 void set_buflocal_tfu_callback(buf_T *buf);