diff -Naur ocaml-4.00.1/otherlibs/labltk/support/cltkEvent.c ocaml-4.00.1-CAMLprim-void/otherlibs/labltk/support/cltkEvent.c
--- ocaml-4.00.1/otherlibs/labltk/support/cltkEvent.c	2013-03-12 18:18:59.000000000 +0100
+++ ocaml-4.00.1-CAMLprim-void/otherlibs/labltk/support/cltkEvent.c	2013-03-12 18:19:31.000000000 +0100
@@ -22,7 +22,7 @@
 #include <alloc.h>
 #include "camltk.h"
 
-CAMLprim value camltk_tk_mainloop(void)
+CAMLprim value camltk_tk_mainloop(value unit)
 {
   CheckInit();
 
diff -Naur ocaml-4.00.1/otherlibs/win32graph/draw.c ocaml-4.00.1-CAMLprim-void/otherlibs/win32graph/draw.c
--- ocaml-4.00.1/otherlibs/win32graph/draw.c	2013-03-12 18:18:31.000000000 +0100
+++ ocaml-4.00.1-CAMLprim-void/otherlibs/win32graph/draw.c	2013-03-12 18:19:18.000000000 +0100
@@ -59,12 +59,12 @@
         return Val_unit;
 }
 
-CAMLprim value caml_gr_current_x(void)
+CAMLprim value caml_gr_current_x(value unit)
 {
         return Val_int(grwindow.grx);
 }
 
-CAMLprim value caml_gr_current_y(void)
+CAMLprim value caml_gr_current_y(value unit)
 {
         return Val_int(grwindow.gry);
 }
@@ -313,7 +313,7 @@
 
 
 
-CAMLprim value caml_gr_get_mousex(void)
+CAMLprim value caml_gr_get_mousex(value unit)
 {
         POINT pt;
         GetCursorPos(&pt);
@@ -321,7 +321,7 @@
         return pt.x;
 }
 
-CAMLprim value caml_gr_get_mousey(void)
+CAMLprim value caml_gr_get_mousey(value unit)
 {
         POINT pt;
         GetCursorPos(&pt);
diff -Naur ocaml-4.00.1/otherlibs/win32graph/open.c ocaml-4.00.1-CAMLprim-void/otherlibs/win32graph/open.c
--- ocaml-4.00.1/otherlibs/win32graph/open.c	2013-03-12 18:18:31.000000000 +0100
+++ ocaml-4.00.1-CAMLprim-void/otherlibs/win32graph/open.c	2013-03-12 18:19:18.000000000 +0100
@@ -39,7 +39,7 @@
 
 static char *szOcamlWindowClass = "OcamlWindowClass";
 static BOOL gr_initialized = 0;
-CAMLprim value caml_gr_clear_graph(void);
+CAMLprim value caml_gr_clear_graph(value unit);
 HANDLE hInst;
 
 HFONT CreationFont(char *name)
@@ -268,7 +268,7 @@
   return Val_unit;
 }
 
-CAMLprim value caml_gr_close_graph(void)
+CAMLprim value caml_gr_close_graph(value unit)
 {
         if (gr_initialized) {
                 PostMessage(grwindow.hwnd, WM_CLOSE, 0, 0);
@@ -277,7 +277,7 @@
         return Val_unit;
 }
 
-CAMLprim value caml_gr_clear_graph(void)
+CAMLprim value caml_gr_clear_graph(value unit)
 {
         gr_check_open();
         if(grremember_mode) {
@@ -291,13 +291,13 @@
         return Val_unit;
 }
 
-CAMLprim value caml_gr_size_x(void)
+CAMLprim value caml_gr_size_x(value unit)
 {
         gr_check_open();
         return Val_int(grwindow.width);
 }
 
-CAMLprim value caml_gr_size_y(void)
+CAMLprim value caml_gr_size_y(value unit)
 {
         gr_check_open();
         return Val_int(grwindow.height);
@@ -312,7 +312,7 @@
   return Val_unit;
 }
 
-CAMLprim value caml_gr_synchronize(void)
+CAMLprim value caml_gr_synchronize(value unit)
 {
         gr_check_open();
         BitBlt(grwindow.gc,0,0,grwindow.width,grwindow.height,
@@ -337,7 +337,7 @@
         return Val_unit;
 }
 
-CAMLprim value caml_gr_sigio_handler(void)
+CAMLprim value caml_gr_sigio_handler(value unit)
 {
         return Val_unit;
 }