Index: src/uk/me/parabola/splitter/RoundingUtils.java
===================================================================
--- src/uk/me/parabola/splitter/RoundingUtils.java	(revision 179)
+++ src/uk/me/parabola/splitter/RoundingUtils.java	(working copy)
@@ -71,12 +71,12 @@
 		int minLat = Math.max(b.getMinLat(), Utils.toMapUnit(-85.0d));
 		int maxLat = Math.min(b.getMaxLat(), Utils.toMapUnit(85.0d));
 
-		int roundedMinLat = roundUp(minLat, shift);
+		int roundedMinLat = roundDown(minLat, shift);
 		int roundedMaxLat = roundUp(maxLat, shift);
 		if ((roundedMinLat & alignment) != (roundedMaxLat & alignment)) {
 			// The new height isn't a multiple of twice the alignment. Fix it by pushing
 			// the tile edge that moved the least out by another 'alignment' units.
-			if (minLat - roundedMinLat < maxLat - roundedMaxLat) {
+			if (minLat - roundedMinLat < roundedMaxLat - maxLat) {
 				roundedMinLat -= alignment;
 			} else {
 				roundedMaxLat += alignment;
@@ -87,7 +87,7 @@
 		assert (roundedMaxLat - roundedMinLat) % doubleAlignment == 0 : "The area's height is not a multiple of " + doubleAlignment;
 
 		int roundedMinLon = roundDown(b.getMinLong(), shift);
-		int roundedMaxLon = roundDown(b.getMaxLong(), shift);
+		int roundedMaxLon = roundUp(b.getMaxLong(), shift);
 		if ((roundedMinLon & alignment) != (roundedMaxLon & alignment)) {
 			// The new width isn't a multiple of twice the alignment. Fix it by pushing
 			// the tile edge that moved the least out by another 'alignment' units.