diff --git a/src/micropolisj/build_tool/Animation.java b/src/micropolisj/build_tool/Animation.java
index 86bafef..a53fe28 100644
--- a/src/micropolisj/build_tool/Animation.java
+++ b/src/micropolisj/build_tool/Animation.java
@@ -11,6 +11,7 @@ class Animation extends TileImage
 {
 	static final int DEFAULT_DURATION = 125;
 	List<Frame> frames = new ArrayList<Frame>();
+	int totalDuration;
 
 	public static Animation load(File aniFile)
 		throws IOException
@@ -21,8 +22,10 @@ class Animation extends TileImage
 		return self;
 	}
 
-	public void addFrame(Frame f)
+	public void addFrame(TileImage img, int duration)
 	{
+		totalDuration += duration;
+		Frame f = new Frame(img, totalDuration);
 		frames.add(f);
 	}
 
@@ -48,11 +51,7 @@ class Animation extends TileImage
 				int duration = tmp != null ? Integer.parseInt(tmp) : DEFAULT_DURATION;
 
 				tmp = in.getElementText();
-				addFrame(
-					new Frame(
-						MakeTiles.parseFrameSpec(tmp),
-						duration
-					));
+				addFrame( MakeTiles.parseFrameSpec(tmp), duration );
 			}
 			else {
 				// unrecognized element
@@ -98,17 +97,4 @@ class Animation extends TileImage
 		// draw nothing
 		return;
 	}
-
-	@Override
-	public int getFrameEndTime(int frameTime)
-	{
-		int t = 0;
-		for (int i = 0; i < frames.size(); i++) {
-			t += frames.get(i).duration;
-			if (frameTime < t) {
-				return t;
-			}
-		}
-		return -1;
-	}
 }
diff --git a/src/micropolisj/build_tool/MakeTiles.java b/src/micropolisj/build_tool/MakeTiles.java
index a6eec56..0a15d77 100644
--- a/src/micropolisj/build_tool/MakeTiles.java
+++ b/src/micropolisj/build_tool/MakeTiles.java
@@ -102,8 +102,6 @@ public class MakeTiles
 
 		@Override
 		public void drawWithTimeTo(Graphics2D gr, int time, int destX, int destY, int srcX, int srcY) { throw new Error("not implemented"); }
-		@Override
-		public int getFrameEndTime(int frameTime) { throw new Error("not implemented"); }
 	}
 
 	static class Composer
@@ -216,21 +214,15 @@ public class MakeTiles
 
 	static TileImage prepareFrames(TileImage ref, Composer c)
 	{
-		if (ref.getFrameEndTime(0) > 0) {
+		if (ref instanceof Animation) {
 
-			Animation ani = new Animation();
-			int t = 0;
-			int n = ref.getFrameEndTime(t);
-			while (n > 0) {
-				TileImageSprite s = c.prepareTile(TILE_SIZE);
-				Animation.Frame f = new Animation.Frame(s, n-t);
-
-				ani.addFrame(f);
-
-				t = n;
-				n = ref.getFrameEndTime(t);
+			Animation mc = (Animation) ref;
+			Animation dest = new Animation();
+			for (Animation.Frame f : mc.frames) {
+				TileImage s = prepareFrames(f.frame, c);
+				dest.addFrame(s, f.duration);
 			}
-			return ani;
+			return dest;
 		}
 		else {
 			TileImageSprite s = c.prepareTile(TILE_SIZE);
diff --git a/src/micropolisj/graphics/TileImage.java b/src/micropolisj/graphics/TileImage.java
index f011b5f..53850a4 100644
--- a/src/micropolisj/graphics/TileImage.java
+++ b/src/micropolisj/graphics/TileImage.java
@@ -13,13 +13,6 @@ public abstract class TileImage
 		drawWithTimeTo(gr, 0, destX, destY, srcX, srcY);
 	}
 
-	/**
-	 * @return the end-time of the animation frame identified by frameTime;
-	 *   -1 if not an animation, or if frameTime is past the end of the animation
-	 */
-	public abstract int getFrameEndTime(int frameTime);
-
-
 	public static class TileImageLayer extends TileImage
 	{
 		public final TileImageLayer below;
@@ -39,27 +32,6 @@ public abstract class TileImage
 			}
 			above.drawWithTimeTo(gr, time, destX, destY, srcX, srcY);
 		}
-
-		@Override
-		public int getFrameEndTime(int frameTime)
-		{
-			if (below == null) {
-				return above.getFrameEndTime(frameTime);
-			}
-
-			int belowEnd = below.getFrameEndTime(frameTime);
-			int aboveEnd = above.getFrameEndTime(frameTime);
-
-			if (belowEnd < 0) {
-				return aboveEnd;
-			}
-			else if (aboveEnd < 0 || belowEnd < aboveEnd) {
-				return belowEnd;
-			}
-			else {
-				return aboveEnd;
-			}
-		}
 	}
 
 	public static class TileImageSprite extends TileImage
@@ -78,11 +50,6 @@ public abstract class TileImage
 		{
 			source.drawWithTimeTo(gr, time, destX, destY, srcX+offsetX, srcY+offsetY);
 		}
-
-		@Override
-		public int getFrameEndTime(int frameTime) {
-			return source.getFrameEndTime(frameTime);
-		}
 	}
 
 	public static class SourceImage extends TileImage
@@ -112,10 +79,5 @@ public abstract class TileImage
 				srcX+basisSize, srcY+basisSize,
 				null);
 		}
-
-		@Override
-		public int getFrameEndTime(int frameTime) {
-			return -1;
-		}
 	}
 }