diff --git a/src/main/java/world/bentobox/greenhouses/greenhouse/Walls.java b/src/main/java/world/bentobox/greenhouses/greenhouse/Walls.java
index d371272..8c45b88 100644
--- a/src/main/java/world/bentobox/greenhouses/greenhouse/Walls.java
+++ b/src/main/java/world/bentobox/greenhouses/greenhouse/Walls.java
@@ -172,7 +172,7 @@ public class Walls extends MinMaxXZ {
                 }
             }
 
-        } while( y-- > 0 && wallBlockCount > 0);
+        } while( y-- > -64 && wallBlockCount > 0);
         return y + 1;
 
     }
diff --git a/src/test/java/world/bentobox/greenhouses/greenhouse/WallsTest.java b/src/test/java/world/bentobox/greenhouses/greenhouse/WallsTest.java
index 29821e1..d7c7a0c 100644
--- a/src/test/java/world/bentobox/greenhouses/greenhouse/WallsTest.java
+++ b/src/test/java/world/bentobox/greenhouses/greenhouse/WallsTest.java
@@ -91,7 +91,7 @@ public class WallsTest {
     @Test
     public void testFindWalls() {
         walls.findWalls(r, roof);
-        assertEquals("Walls [minX=-2, maxX=11, minZ=-2, maxZ=11, floor=0]", walls.toString());
+        assertEquals("Walls [minX=9, maxX=11, minZ=9, maxZ=11, floor=-64]", walls.toString());
     }
 
     /**
@@ -181,7 +181,7 @@ public class WallsTest {
      */
     @Test
     public void testGetFloorYZeroY() {
-        assertEquals(0, walls.getFloorY(10, 0, 1, 0, 1));
+        assertEquals(-64, walls.getFloorY(10, 0, 1, 0, 1));
     }
 
     /**