diff --git a/frontends/riscos/plotters.c b/frontends/riscos/plotters.c
index 2b306827d..25c953f97 100644
--- a/frontends/riscos/plotters.c
+++ b/frontends/riscos/plotters.c
@@ -110,12 +110,17 @@ ro_plot_clip(const struct redraw_context *ctx, const struct rect *clip)
 	os_error *error;
 	char buf[12];
 
-	int clip_x0 = ro_plot_origin_x + clip->x0 * 2;
-	int clip_y0 = ro_plot_origin_y - clip->y0 * 2 - 1;
-	int clip_x1 = ro_plot_origin_x + clip->x1 * 2 - 1;
-	int clip_y1 = ro_plot_origin_y - clip->y1 * 2;
+	int clip_x0 = clip->x0 * 2;
+	int clip_y0 = clip->y1 * 2;
+	int clip_x1 = clip->x1 * 2;
+	int clip_y1 = clip->y0 * 2;
 
-	if (clip_x1 < clip_x0 || clip_y0 < clip_y1) {
+	clip_x0 = ro_plot_origin_x + clip_x0;
+	clip_y0 = ro_plot_origin_y - clip_y0;
+	clip_x1 = ro_plot_origin_x + clip_x1 - 1;
+	clip_y1 = ro_plot_origin_y - clip_y1 - 1;
+
+	if (clip_x1 < clip_x0 || clip_y1 < clip_y0) {
 		NSLOG(netsurf, INFO, "bad clip rectangle %i %i %i %i",
 		      clip_x0, clip_y0, clip_x1, clip_y1);
 		return NSERROR_BAD_SIZE;
@@ -124,12 +129,12 @@ ro_plot_clip(const struct redraw_context *ctx, const struct rect *clip)
 	buf[0] = os_VDU_SET_GRAPHICS_WINDOW;
 	buf[1] = clip_x0;
 	buf[2] = clip_x0 >> 8;
-	buf[3] = clip_y1;
-	buf[4] = clip_y1 >> 8;
+	buf[3] = clip_y0;
+	buf[4] = clip_y0 >> 8;
 	buf[5] = clip_x1;
 	buf[6] = clip_x1 >> 8;
-	buf[7] = clip_y0;
-	buf[8] = clip_y0 >> 8;
+	buf[7] = clip_y1;
+	buf[8] = clip_y1 >> 8;
 
 	error = xos_writen(buf, 9);
 	if (error) {
@@ -365,7 +370,7 @@ ro_plot_rectangle(const struct redraw_context *ctx,
 
 		error = xos_plot(os_MOVE_TO,
 				 ro_plot_origin_x + rect->x0 * 2,
-				 ro_plot_origin_y - rect->y0 * 2 - 1);
+				 ro_plot_origin_y - rect->y1 * 2);
 		if (error) {
 			NSLOG(netsurf, INFO, "xos_plot: 0x%x: %s",
 			      error->errnum, error->errmess);
@@ -374,7 +379,7 @@ ro_plot_rectangle(const struct redraw_context *ctx,
 
 		error = xos_plot(os_PLOT_RECTANGLE | os_PLOT_TO,
 				 ro_plot_origin_x + rect->x1 * 2 - 1,
-				 ro_plot_origin_y - rect->y1 * 2);
+				 ro_plot_origin_y - rect->y0 * 2 - 1);
 		if (error) {
 			NSLOG(netsurf, INFO, "xos_plot: 0x%x: %s",
 			      error->errnum, error->errmess);