diff --git a/implementations/uvm-ncc/graphics.h b/implementations/uvm-ncc/graphics.h
index 1c27b46..f747b21 100644
--- a/implementations/uvm-ncc/graphics.h
+++ b/implementations/uvm-ncc/graphics.h
@@ -107,27 +107,30 @@ carefree_wu_line(u32* dest, size_t dest_stride, u64 x, u64 y, u64 w, u64 h, u32
 	// > We translate the point (x0, y0) to the origin,
 	// so y = kx where k = h/w with k <= 1
 	u16 k = 0xFFFF * h / w;
-	//print_i64(w); print_str(" x ");	print_i64(h); print_endl();
-	print_i64(k>>8); print_endl();
-	u64 x1 = x + w;
-	u64 y1 = y + h;
+	u64 x1 = x + w - 1;
+	u64 y1 = y + h - 1;
 	u16 d = 0;
 	while (x1 > x) {
-		//print_i64(d); print_endl();
-		if (d) {
-			plot_pixel(dest, dest_stride,  x,  y, color, d >> 8);
-			plot_pixel(dest, dest_stride, x1, y1, color, d >> 8);
-		}
-		plot_pixel(dest, dest_stride,  x,  y - 1, color, 0xFF - (d >> 8));
-		plot_pixel(dest, dest_stride, x1, y1 - 1, color, 0xFF - (d >> 8));
+		plot_pixel(dest, dest_stride, x, y + 1, color,         d >> 8);
+		plot_pixel(dest, dest_stride, x, y,     color, 0xFF - (d >> 8));
+		plot_pixel(dest, dest_stride, x1, y1, color,         d >> 8);
+		plot_pixel(dest, dest_stride, x1, y1 + 1,     color, 0xFF - (d >> 8));
 		++x;
-		--x1;
-		d = d + k;
-		if (d > 0xFFFF) {
+		x1 = x1 - 1;  // "--x1" didn't work here, x1 remained unchanged.
+		if (d + k >= 0xFFFF) {
 			d = 0;
 			// opposite (de-)increment because computer y is negative cartesian y
 			++y;
-			--y1;
+			y1 = y1 - 1;
+		} else {
+			d = d + k;
 		}
 	}
 }
+
+
+
+
+
+
+
diff --git a/implementations/uvm-ncc/xerblin.c b/implementations/uvm-ncc/xerblin.c
index 19a6529..9a862bf 100644
--- a/implementations/uvm-ncc/xerblin.c
+++ b/implementations/uvm-ncc/xerblin.c
@@ -105,7 +105,8 @@ main()
 	u64 h = 4 + 4 * font_Inconsolata_22_height;
 	carefree_draw_box(frame_buffer, FRAME_WIDTH, 126, 126, w, h, WHITE);
 	w = 200;
-	for (w = 101; w < (FRAME_WIDTH - 10); w = w + 3) {
+	//carefree_wu_line(frame_buffer, FRAME_WIDTH, 10, 256, 200, 100, WHITE);
+	for (w = 101; w < (FRAME_WIDTH - 10); w = w + 50) {
 		carefree_wu_line(frame_buffer, FRAME_WIDTH, 10, 256, w, 100, WHITE);
 	}
 	window_draw_frame(wid, frame_buffer);