diff --git a/doc/funcref.sgml b/doc/funcref.sgml
index adbd7eeaa..60b69409c 100644
--- a/doc/funcref.sgml
+++ b/doc/funcref.sgml
@@ -5357,7 +5357,7 @@ tgi_init(); //Set up the default palette and clear the screen.
 <descrip>
 <tag/Function/Platform dependent code extensions.
 <tag/Header/<tt/<ref id="tgi.h" name="tgi.h">/
-<tag/Declaration/<tt/unsigned __fastcall__ tgi_ioctl (unsigned char code, unsigned val);/
+<tag/Declaration/<tt/unsigned __fastcall__ tgi_ioctl (unsigned char code, void* data);/
 <tag/Description/Some platforms have extra display hardware that is not
 supported by standard tgi functions. You can extend the driver to support
 this extra hardware using tgi_ioctl functions.
@@ -5369,12 +5369,12 @@ be used in presence of a prototype.
 <tag/Availability/cc65
 <tag/See also/Other tgi functions.
 <tag/Example/<verb>
-#define tgi_sprite(spr) tgi_ioctl(0, (unsigned)(spr))
-#define tgi_flip() tgi_ioctl(1, 0)
-#define tgi_setbgcolor(bgcol) tgi_ioctl(2, (unsigned)(bgcol))
-#define tgi_setframerate(rate) tgi_ioctl(3, (unsigned)(rate))
-#define tgi_busy() tgi_ioctl(4, 0)
-#define tgi_updatedisplay() tgi_ioctl(4, 1)
+#define tgi_sprite(spr) tgi_ioctl(0, (void*)(spr))
+#define tgi_flip() tgi_ioctl(1, (void*)0)
+#define tgi_setbgcolor(bgcol) tgi_ioctl(2, (void*)(bgcol))
+#define tgi_setframerate(rate) tgi_ioctl(3, (void*)(rate))
+#define tgi_busy() tgi_ioctl(4, (void*)0)
+#define tgi_updatedisplay() tgi_ioctl(4, (void*)1)
 if (!tgi_busy()) {
   tgi_sprite(&amp;background);
   tgi_setcolor(TGI_COLOR_BLUE);
@@ -5522,7 +5522,7 @@ be used in presence of a prototype.
 <tag/Header/<tt/<ref id="tgi.h" name="tgi.h">/
 <tag/Declaration/<tt/void __fastcall__ tgi_pie slice (int x, int y,
 unsigned char rx, unsigned char ry, unsigned sa, unsigned ea);/
-<tag/Description/The function draws an elliptic pie slice with center at x/y 
+<tag/Description/The function draws an elliptic pie slice with center at x/y
 and radii rx/ry using the current drawing color. The pie slice covers the angle
 between sa and ea (startangle and endangle), which must be in the range
 0..360.
diff --git a/include/lynx.h b/include/lynx.h
index 303260e33..3708b41ba 100644
--- a/include/lynx.h
+++ b/include/lynx.h
@@ -103,13 +103,13 @@ void __fastcall__ lynx_eeprom_erase (unsigned char cell);
 /*                           TGI extras                                      */
 /*****************************************************************************/
 
-#define tgi_sprite(spr) tgi_ioctl(0, (unsigned)(spr))
-#define tgi_flip() tgi_ioctl(1, 0)
-#define tgi_setbgcolor(bgcol) tgi_ioctl(2, (unsigned)(bgcol))
-#define tgi_setframerate(rate) tgi_ioctl(3, (unsigned)(rate))
-#define tgi_busy() tgi_ioctl(4, 0)
-#define tgi_updatedisplay() tgi_ioctl(4, 1)
-#define tgi_setcollisiondetection(active) tgi_ioctl(5, (unsigned)(active))
+#define tgi_sprite(spr) tgi_ioctl(0, spr)
+#define tgi_flip() tgi_ioctl(1, (void*)0)
+#define tgi_setbgcolor(bgcol) tgi_ioctl(2, (void*)(bgcol))
+#define tgi_setframerate(rate) tgi_ioctl(3, (void*)(rate))
+#define tgi_busy() tgi_ioctl(4, (void*)0)
+#define tgi_updatedisplay() tgi_ioctl(4, (void*)1)
+#define tgi_setcollisiondetection(active) tgi_ioctl(5, (void*)(active))
 
 /* End of lynx.h */
 #endif
diff --git a/include/tgi.h b/include/tgi.h
index 46c7fa044..19630d0d9 100644
--- a/include/tgi.h
+++ b/include/tgi.h
@@ -270,7 +270,7 @@ void __fastcall__ tgi_outtextxy (int x, int y, const char* s);
  * the end of the text.
  */
 
-unsigned __fastcall__ tgi_ioctl (unsigned char code, unsigned val);
+unsigned __fastcall__ tgi_ioctl (unsigned char code, void* data);
 /* Call the driver specific control function. What this function does for
  * a specific code depends on the driver. The driver will set an error
  * for unknown codes or values.
diff --git a/libsrc/tgi/tgi_ioctl.s b/libsrc/tgi/tgi_ioctl.s
index 35542f3ce..fd4db7dcd 100644
--- a/libsrc/tgi/tgi_ioctl.s
+++ b/libsrc/tgi/tgi_ioctl.s
@@ -1,7 +1,7 @@
 ;
 ; Ullrich von Bassewitz, 2004-10-14
 ;
-; unsigned __fastcall__ tgi_ioctl (unsigned char code, unsigned val);
+; unsigned __fastcall__ tgi_ioctl (unsigned char code, void* data);
 ; /* Call the driver specific control function. What this function does for
 ;  * a specific code depends on the driver. The driver will set an error
 ;  * for unknown codes or values.