--- a/src/if_perl.xs
+++ b/src/if_perl.xs
@@ -631,8 +631,7 @@ perl_runtime_link_init(char *libname, in
  * There were no DLL loaded, return FALSE.
  */
     int
-perl_enabled(verbose)
-    int		verbose;
+perl_enabled(int verbose)
 {
     return perl_runtime_link_init((char *)p_perldll, verbose) == OK;
 }
@@ -644,7 +643,7 @@ perl_enabled(verbose)
  * there's nothing to actually parse.
  */
     static void
-perl_init()
+perl_init(void)
 {
     char *bootargs[] = { "VI", NULL };
     int argc = 3;
@@ -670,7 +669,7 @@ perl_init()
  * perl_end(): clean up after ourselves
  */
     void
-perl_end()
+perl_end(void)
 {
     if (perl_interp)
     {
@@ -696,9 +695,9 @@ perl_end()
  * split at '\n' first though.
  */
     void
-msg_split(s, attr)
-    char_u	*s;
-    int		attr;	/* highlighting attributes */
+msg_split(
+    char_u	*s,
+    int		attr)	/* highlighting attributes */
 {
     char *next;
     char *token = (char *)s;
@@ -719,10 +718,10 @@ msg_split(s, attr)
  * work properly.
  */
     char_u *
-eval_to_string(arg, nextcmd, dolist)
-    char_u	*arg UNUSED;
-    char_u	**nextcmd UNUSED;
-    int		dolist UNUSED;
+eval_to_string(
+    char_u	*arg UNUSED,
+    char_u	**nextcmd UNUSED,
+    int		dolist UNUSED)
 {
     return NULL;
 }
@@ -740,9 +739,7 @@ eval_to_string(arg, nextcmd, dolist)
  */
 
     static SV *
-newWINrv(rv, ptr)
-    SV	    *rv;
-    win_T   *ptr;
+newWINrv(SV *rv, win_T *ptr)
 {
     sv_upgrade(rv, SVt_RV);
     if (ptr->w_perl_private == NULL)
@@ -758,9 +755,7 @@ newWINrv(rv, ptr)
 }
 
     static SV *
-newBUFrv(rv, ptr)
-    SV	    *rv;
-    buf_T   *ptr;
+newBUFrv(SV *rv, buf_T *ptr)
 {
     sv_upgrade(rv, SVt_RV);
     if (ptr->b_perl_private == NULL)
@@ -780,8 +775,7 @@ newBUFrv(rv, ptr)
  *	Remove all references to the window to be destroyed
  */
     void
-perl_win_free(wp)
-    win_T *wp;
+perl_win_free(win_T *wp)
 {
     if (wp->w_perl_private)
 	sv_setiv((SV *)wp->w_perl_private, 0);
@@ -789,8 +783,7 @@ perl_win_free(wp)
 }
 
     void
-perl_buf_free(bp)
-    buf_T *bp;
+perl_buf_free(buf_T *bp)
 {
     if (bp->b_perl_private)
 	sv_setiv((SV *)bp->b_perl_private, 0);
@@ -834,7 +827,7 @@ struct ufuncs cb_funcs = { cur_val, 0, 1
  * Make the magical main::curwin and main::curbuf variables
  */
     static void
-VIM_init()
+VIM_init(void)
 {
     static char cw[] = "main::curwin";
     static char cb[] = "main::curbuf";
@@ -866,8 +859,7 @@ static char *e_noperl = N_("Sorry, this 
  * ":perl"
  */
     void
-ex_perl(eap)
-    exarg_T	*eap;
+ex_perl(exarg_T *eap)
 {
     char	*err;
     char	*script;
@@ -947,8 +939,7 @@ ex_perl(eap)
 }
 
     static int
-replace_line(line, end)
-    linenr_T	*line, *end;
+replace_line(linenr_T *line, linenr_T *end)
 {
     char *str;
 
@@ -989,8 +980,7 @@ ref_map_free(void)
 }
 
     static struct ref_map_S *
-ref_map_find_SV(sv)
-    SV	*const sv;
+ref_map_find_SV(SV *const sv)
 {
     struct ref_map_S *refs = ref_map;
     int count = 350;
@@ -1016,9 +1006,7 @@ ref_map_find_SV(sv)
 }
 
     static int
-perl_to_vim(sv, rettv)
-    SV		*sv;
-    typval_T	*rettv;
+perl_to_vim(SV *sv, typval_T *rettv)
 {
     if (SvROK(sv))
 	sv = SvRV(sv);
@@ -1171,9 +1159,7 @@ perl_to_vim(sv, rettv)
  * "perleval()"
  */
     void
-do_perleval(str, rettv)
-    char_u	*str;
-    typval_T	*rettv;
+do_perleval(char_u *str, typval_T *rettv)
 {
     char	*err = NULL;
     STRLEN	err_len = 0;
@@ -1241,8 +1227,7 @@ do_perleval(str, rettv)
  * ":perldo".
  */
     void
-ex_perldo(eap)
-    exarg_T	*eap;
+ex_perldo(exarg_T *eap)
 {
     STRLEN	length;
     SV		*sv;
@@ -1314,9 +1299,21 @@ err:
 }
 
 #ifndef FEAT_WINDOWS
-int win_valid(win_T *w) { return TRUE; }
-int win_count() { return 1; }
-win_T *win_find_nr(int n) { return curwin; }
+    int
+win_valid(win_T *w)
+{
+    return TRUE;
+}
+    int
+win_count(void)
+{
+    return 1;
+}
+    win_T *
+win_find_nr(int n)
+{
+    return curwin;
+}
 #endif
 
 XS(boot_VIM);
@@ -1513,8 +1510,7 @@ SetHeight(win, height)
     curwin = savewin;
 
 void
-Cursor(win, ...)
-    VIWIN win
+Cursor(VIWIN win, ...)
 
     PPCODE:
     if (items == 1)