diff --git a/cmd/mtwebmapper/tilesupdater.go b/cmd/mtwebmapper/tilesupdater.go
index 8b09a0e..5150394 100644
--- a/cmd/mtwebmapper/tilesupdater.go
+++ b/cmd/mtwebmapper/tilesupdater.go
@@ -54,7 +54,7 @@ type xzc struct {
 }
 
 type xzm struct {
-	P    xz
+	xz
 	Mask uint16
 }
 
@@ -70,8 +70,8 @@ func (c xz) parent() xzm {
 	xp, xr := c.X>>1, uint16(c.X&1)
 	zp, zr := c.Z>>1, uint16(c.Z&1)
 	return xzm{
-		P:    xz{X: xp, Z: zp},
-		Mask: 1 << (zr<<1 | xr)}
+		xz{X: xp, Z: zp},
+		1 << (zr<<1 | xr)}
 }
 
 func newTileUpdater(
@@ -224,7 +224,7 @@ func (tu *tileUpdater) doUpdates() {
 		parentJobs := make(map[xz]uint16)
 		for i := range actChs {
 			pxz := actChs[i].parent()
-			parentJobs[pxz.P] |= pxz.Mask
+			parentJobs[pxz.xz] |= pxz.Mask
 		}
 
 		for level := 7; level >= 0; level-- {
@@ -235,9 +235,9 @@ func (tu *tileUpdater) doUpdates() {
 			}
 			ppJobs := make(map[xz]uint16)
 			for c, mask := range parentJobs {
-				pJobs <- xzm{P: c, Mask: mask}
+				pJobs <- xzm{c, mask}
 				pxz := c.parent()
-				ppJobs[pxz.P] |= pxz.Mask
+				ppJobs[pxz.xz] |= pxz.Mask
 			}
 			close(pJobs)
 			done.Wait()
@@ -291,8 +291,8 @@ func (tu *tileUpdater) updatePyramidTile(scratch, resized *image.RGBA, level int
 	origPath := filepath.Join(
 		tu.mapDir,
 		strconv.Itoa(level),
-		strconv.Itoa(int(j.P.X)),
-		strconv.Itoa(int(j.P.Z))+".png")
+		strconv.Itoa(int(j.X)),
+		strconv.Itoa(int(j.Z))+".png")
 
 	sr := resized.Bounds()
 	levelDir := strconv.Itoa(level + 1)
@@ -300,7 +300,7 @@ func (tu *tileUpdater) updatePyramidTile(scratch, resized *image.RGBA, level int
 		if j.Mask&(1<<i) != 0 {
 			//log.Printf("level %d: modified %d\n", level, i)
 			o := ofs[i]
-			bx, bz := int(2*j.P.X), int(2*j.P.Z)
+			bx, bz := int(2*j.X), int(2*j.Z)
 			path := filepath.Join(
 				tu.mapDir,
 				levelDir,