diff --git a/src/micropolisj/engine/ExplosionSprite.java b/src/micropolisj/engine/ExplosionSprite.java
index d36105a..ae77ffa 100644
--- a/src/micropolisj/engine/ExplosionSprite.java
+++ b/src/micropolisj/engine/ExplosionSprite.java
@@ -56,7 +56,7 @@ public class ExplosionSprite extends Sprite
 		int t = z & LOMASK;
 		if ((z & BURNBIT) == 0 && t != DIRT)
 			return;
-		if ((z & ZONEBIT) != 0)
+		if (isZoneCenter(z))
 			return;
 		city.setTile(xpos, ypos, (char)(FIRE + city.PRNG.nextInt(4) + ANIMBIT));
 	}
diff --git a/src/micropolisj/engine/MapScanner.java b/src/micropolisj/engine/MapScanner.java
index d88be18..8cc58e4 100644
--- a/src/micropolisj/engine/MapScanner.java
+++ b/src/micropolisj/engine/MapScanner.java
@@ -78,7 +78,7 @@ class MapScanner
 				return;
 			}
 
-			if ((cchr & ZONEBIT) != 0)
+			if (isZoneCenter(cchr))
 			{
 				doZone();
 				return;
@@ -192,7 +192,7 @@ class MapScanner
 
 				int c = city.map[ytem][xtem];
 				if ((c & BURNBIT) != 0) {
-					if ((c & ZONEBIT) != 0) {
+					if (isZoneCenter(c)) {
 						city.killZone(xtem, ytem, c);
 						if ((c & LOMASK) > IZB) { //explode
 							city.makeExplosion(xtem, ytem);
@@ -234,7 +234,7 @@ class MapScanner
 						if (((c & BURNBIT) != 0) || c == DIRT ||
 							(t >= WOODS5 && t < FLOOD))
 						{
-							if ((c & ZONEBIT) != 0) {
+							if (isZoneCenter(c)) {
 								city.killZone(xx, yy, c);
 							}
 							city.setTile(xx, yy, (char)(FLOOD + PRNG.nextInt(3)));
@@ -755,8 +755,9 @@ class MapScanner
 				if (city.testBounds(xx, yy))
 				{
 					int thCh = city.map[yy][xx];
-					if ((thCh & ZONEBIT) != 0)
+					if (isZoneCenter(thCh)) {
 						continue;
+					}
 
 					if ((thCh & ANIMBIT) != 0)
 						continue;
diff --git a/src/micropolisj/engine/Micropolis.java b/src/micropolisj/engine/Micropolis.java
index eda3bdd..c18e389 100644
--- a/src/micropolisj/engine/Micropolis.java
+++ b/src/micropolisj/engine/Micropolis.java
@@ -672,7 +672,7 @@ public class Micropolis
 			for (int y = 0; y < height; y++)
 			{
 				char tile = map[y][x];
-				if ((tile & ZONEBIT) != 0)
+				if (isZoneCenter(tile))
 				{
 					tile &= LOMASK;
 					int den = computePopDen(x, y, (char)tile) * 8;
@@ -1838,8 +1838,9 @@ public class Micropolis
 				continue;
 
 			int t = map[y][x];
-			if ((t & ZONEBIT) != 0)
+			if (isZoneCenter(t)) {
 				continue;
+			}
 			if ((t & BURNBIT) != 0 || t == DIRT) {
 				setTile(x, y, RADTILE);
 			}
@@ -2212,7 +2213,7 @@ public class Micropolis
 			int x = PRNG.nextInt(getWidth());
 			int y = PRNG.nextInt(getHeight());
 			int tile = map[y][x];
-			if ((tile & ZONEBIT) == 0 && (tile & BURNBIT) != 0)
+			if (!isZoneCenter(tile) && (tile & BURNBIT) != 0)
 			{
 				tile &= LOMASK;
 				if (tile > 21 && tile < LASTZONE) {
diff --git a/src/micropolisj/engine/Sprite.java b/src/micropolisj/engine/Sprite.java
index 6f105f0..a45423c 100644
--- a/src/micropolisj/engine/Sprite.java
+++ b/src/micropolisj/engine/Sprite.java
@@ -182,7 +182,7 @@ public abstract class Sprite
 			if ((z & BURNBIT) == 0) {
 				return; //cannot destroy it
 			}
-			if ((z & ZONEBIT) != 0) {
+			if (isZoneCenter(z)) {
 				city.killZone(xpos, ypos, z);
 				if (t > RZB) {
 					city.makeExplosion(xpos, ypos);