diff --git a/sc2/src/sc2code/flash.c b/sc2/src/sc2code/flash.c
index fa1fd0e8a..2ed9ced55 100644
--- a/sc2/src/sc2code/flash.c
+++ b/sc2/src/sc2code/flash.c
@@ -34,7 +34,7 @@
 
 
 extern void arith_frame_blit (FRAME srcFrame, const RECT *rsrc,
-		FRAME dstFrame, RECT *rdst, int num, int denom);
+		FRAME dstFrame, const RECT *rdst, int num, int denom);
 
 static FlashContext *Flash_create (CONTEXT gfxContext, FRAME parent);
 static void Flash_fixState (FlashContext *context);
diff --git a/sc2/src/sc2code/planets/pl_stuff.c b/sc2/src/sc2code/planets/pl_stuff.c
index b1996f82b..33e551b65 100644
--- a/sc2/src/sc2code/planets/pl_stuff.c
+++ b/sc2/src/sc2code/planets/pl_stuff.c
@@ -37,8 +37,8 @@ extern DWORD frame_mapRGBA (FRAME FramePtr, UBYTE r, UBYTE g,
 		UBYTE b, UBYTE a);
 extern void fill_frame_rgb (FRAME FramePtr, DWORD color, int x0, int y0,
 		int x, int y);
-extern void arith_frame_blit (FRAME srcFrame, RECT *rsrc, FRAME dstFrame,
-		RECT *rdst, int num, int denom);
+extern void arith_frame_blit (FRAME srcFrame, const RECT *rsrc,
+		FRAME dstFrame, const RECT *rdst, int num, int denom);
 
 
 // RotatePlanet
diff --git a/sc2/src/sc2code/planets/plangen.c b/sc2/src/sc2code/planets/plangen.c
index f6dcae048..e2ec5a345 100644
--- a/sc2/src/sc2code/planets/plangen.c
+++ b/sc2/src/sc2code/planets/plangen.c
@@ -48,8 +48,8 @@ extern void process_rgb_bmp (FRAME FramePtr, DWORD *rgba, int maxx, int maxy);
 extern FRAME stretch_frame (FRAME FramePtr, int neww, int newh, int destroy);
 extern void fill_frame_rgb (FRAME FramePtr, DWORD color, int x0, int y0,
 		int x, int y);
-extern void arith_frame_blit (FRAME srcFrame, RECT *rsrc, FRAME dstFrame,
-		RECT *rdst, int num, int denom);
+extern void arith_frame_blit (FRAME srcFrame, const RECT *rsrc,
+		FRAME dstFrame, const RECT *rdst, int num, int denom);
 extern void getpixelarray (void *map, int Bpp, FRAME FramePtr,
 		int width, int height);
 
diff --git a/sc2/src/sc2code/sis.c b/sc2/src/sc2code/sis.c
index 6182a95c9..aa69efcf8 100644
--- a/sc2/src/sc2code/sis.c
+++ b/sc2/src/sc2code/sis.c
@@ -1296,8 +1296,8 @@ static int flash_changed;
 Mutex flash_mutex = 0;
 // XXX: these are currently defined in libs/graphics/sdl/3do_getbody.c
 //  they should be sorted out and cleaned up at some point
-extern void arith_frame_blit (FRAME srcFrame, RECT *rsrc, FRAME dstFrame,
-		RECT *rdst, int num, int denom);
+extern void arith_frame_blit (FRAME srcFrame, const RECT *rsrc,
+		FRAME dstFrame, const RECT *rdst, int num, int denom);
 
 static int
 flash_rect_func (void *data)