Index: head/sys/dev/vt/hw/fb/vt_fb.c
===================================================================
--- head/sys/dev/vt/hw/fb/vt_fb.c
+++ head/sys/dev/vt/hw/fb/vt_fb.c
@@ -264,46 +264,40 @@
 {
 	struct fb_info *info;
 	uint32_t fgc, bgc, cc, o;
-	int c, l, bpp, bpl;
-	u_long line;
-	uint8_t b, m;
-	const uint8_t *ch;
+	int bpp, bpl, xi, yi;
+	int bit, byte;
 
 	info = vd->vd_softc;
 	bpp = FBTYPE_GET_BYTESPP(info);
 	fgc = info->fb_cmap[fg];
 	bgc = info->fb_cmap[bg];
-	b = m = 0;
-	bpl = (width + 7) >> 3; /* Bytes per source line. */
+	bpl = (width + 7) / 8; /* Bytes per source line. */
 
 	if (info->fb_flags & FB_FLAG_NOWRITE)
 		return;
 
 	KASSERT((info->fb_vbase != 0), ("Unmapped framebuffer"));
 
-	line = (info->fb_stride * y) + (x * bpp);
-	for (l = 0;
-	    l < height && y + l < vw->vw_draw_area.tr_end.tp_row;
-	    l++) {
-		ch = pattern;
-		for (c = 0;
-		    c < width && x + c < vw->vw_draw_area.tr_end.tp_col;
-		    c++) {
-			if (c % 8 == 0)
-				b = *ch++;
-			else
-				b <<= 1;
-			if (mask != NULL) {
-				if (c % 8 == 0)
-					m = *mask++;
-				else
-					m <<= 1;
-				/* Skip pixel write, if mask has no bit set. */
-				if ((m & 0x80) == 0)
-					continue;
-			}
-			o = line + (c * bpp);
-			cc = b & 0x80 ? fgc : bgc;
+	/* Bound by right and bottom edges. */
+	if (y + height > vw->vw_draw_area.tr_end.tp_row) {
+		if (y >= vw->vw_draw_area.tr_end.tp_row)
+			return;
+		height = vw->vw_draw_area.tr_end.tp_row - y;
+	}
+	if (x + width > vw->vw_draw_area.tr_end.tp_col) {
+		if (x >= vw->vw_draw_area.tr_end.tp_col)
+			return;
+		width = vw->vw_draw_area.tr_end.tp_col - x;
+	}
+	for (yi = 0; yi < height; yi++) {
+		for (xi = 0; xi < width; xi++) {
+			byte = yi * bpl + xi / 8;
+			bit = 0x80 >> (xi % 8);
+			/* Skip pixel write, if mask bit not set. */
+			if (mask != NULL && (mask[byte] & bit) == 0)
+				continue;
+			o = (y + yi) * info->fb_stride + (x + xi) * bpp;
+			cc = pattern[byte] & bit ? fgc : bgc;
 
 			switch(bpp) {
 			case 1:
@@ -326,8 +320,6 @@
 				break;
 			}
 		}
-		line += info->fb_stride;
-		pattern += bpl;
 	}
 }