diff --git a/src/main/java/world/bentobox/greenhouses/data/Greenhouse.java b/src/main/java/world/bentobox/greenhouses/data/Greenhouse.java
index 2badd4e..a0f81ad 100644
--- a/src/main/java/world/bentobox/greenhouses/data/Greenhouse.java
+++ b/src/main/java/world/bentobox/greenhouses/data/Greenhouse.java
@@ -249,4 +249,18 @@ public class Greenhouse implements DataObject {
     public Map<Material, Integer> getMissingBlocks() {
         return missingBlocks;
     }
+
+    /**
+     * Check if a location is a wall or roof block
+     * @param l - location
+     * @return true if wall or roof block
+     */
+    public boolean isRoofOrWallBlock(Location l) {
+        return ((l.getBlockY() == getCeilingHeight() - 1)
+                || l.getBlockX() == (int)getBoundingBox().getMinX()
+                || l.getBlockX() == (int)getBoundingBox().getMaxX() - 1
+                || l.getBlockZ() == (int)getBoundingBox().getMinZ()
+                || l.getBlockZ() == (int)getBoundingBox().getMaxZ() - 1
+                );
+    }
 }
diff --git a/src/main/java/world/bentobox/greenhouses/listeners/GreenhouseEvents.java b/src/main/java/world/bentobox/greenhouses/listeners/GreenhouseEvents.java
index 5c15d33..c5eb3ec 100644
--- a/src/main/java/world/bentobox/greenhouses/listeners/GreenhouseEvents.java
+++ b/src/main/java/world/bentobox/greenhouses/listeners/GreenhouseEvents.java
@@ -161,17 +161,11 @@ public class GreenhouseEvents implements Listener {
     @EventHandler(priority = EventPriority.NORMAL, ignoreCancelled=true)
     public void onBlockBreak(final BlockBreakEvent e) {
         User user = User.getInstance(e.getPlayer());
-        addon.getManager().getMap().getGreenhouse(e.getBlock().getLocation()).ifPresent(g -> {
-            // Check to see if wall or roof block broken
-            if ((e.getBlock().getLocation().getBlockY() == g.getCeilingHeight() - 1)
-                    || e.getBlock().getLocation().getBlockX() == (int)g.getBoundingBox().getMinX()
-                    || e.getBlock().getLocation().getBlockX() == (int)g.getBoundingBox().getMaxX() - 1
-                    || e.getBlock().getLocation().getBlockZ() == (int)g.getBoundingBox().getMinZ()
-                    || e.getBlock().getLocation().getBlockZ() == (int)g.getBoundingBox().getMaxZ() - 1
-                    ) {
-                user.sendMessage("greenhouses.event.broke", BIOME, Util.prettifyText(g.getOriginalBiome().name()));
-                addon.getManager().removeGreenhouse(g);
-            }
+        addon.getManager().getMap().getGreenhouse(e.getBlock().getLocation())
+        .filter(g -> g.isRoofOrWallBlock(e.getBlock().getLocation()))
+        .ifPresent(g -> {
+            user.sendMessage("greenhouses.event.broke", BIOME, Util.prettifyText(g.getOriginalBiome().name()));
+            addon.getManager().removeGreenhouse(g);
         });
     }
 
diff --git a/src/main/java/world/bentobox/greenhouses/listeners/GreenhouseGuard.java b/src/main/java/world/bentobox/greenhouses/listeners/GreenhouseGuard.java
index c194359..13c533f 100644
--- a/src/main/java/world/bentobox/greenhouses/listeners/GreenhouseGuard.java
+++ b/src/main/java/world/bentobox/greenhouses/listeners/GreenhouseGuard.java
@@ -2,10 +2,13 @@ package world.bentobox.greenhouses.listeners;
 
 import java.util.Optional;
 
+import org.bukkit.Location;
+import org.bukkit.block.Block;
 import org.bukkit.event.EventHandler;
 import org.bukkit.event.EventPriority;
 import org.bukkit.event.Listener;
 import org.bukkit.event.block.BlockFromToEvent;
+import org.bukkit.event.block.BlockPistonExtendEvent;
 
 import world.bentobox.greenhouses.Greenhouses;
 import world.bentobox.greenhouses.data.Greenhouse;
@@ -18,7 +21,7 @@ public class GreenhouseGuard implements Listener {
     }
 
     // Stop lava flow or water into or out of a greenhouse
-    @EventHandler(priority = EventPriority.NORMAL)
+    @EventHandler(priority = EventPriority.NORMAL, ignoreCancelled = true)
     public void onFlow(final BlockFromToEvent e) {
         // Flow may be allowed anyway
         if (addon.getSettings().isAllowFlowIn() && addon.getSettings().isAllowFlowOut()) {
@@ -52,6 +55,21 @@ public class GreenhouseGuard implements Listener {
         e.setCancelled(true);
     }
 
+    /**
+     * Prevents pistons from pushing greenhouse wall or roof blocks
+     * @param e - event
+     */
+    @EventHandler(priority = EventPriority.NORMAL, ignoreCancelled = true)
+    public void onPistonPush(BlockPistonExtendEvent e) {
+        e.setCancelled(e.getBlocks().stream()
+                .map(Block::getLocation)
+                .filter(this::inGreenhouse)
+                .findFirst()
+                .isPresent());
+    }
 
+    private boolean inGreenhouse(Location l) {
+        return addon.getManager().getMap().getGreenhouse(l).map(g -> g.isRoofOrWallBlock(l)).orElse(false);
+    }
 }
 
diff --git a/src/test/java/world/bentobox/greenhouses/listeners/GreenhouseEventsTest.java b/src/test/java/world/bentobox/greenhouses/listeners/GreenhouseEventsTest.java
index 9985aa1..4a6af13 100644
--- a/src/test/java/world/bentobox/greenhouses/listeners/GreenhouseEventsTest.java
+++ b/src/test/java/world/bentobox/greenhouses/listeners/GreenhouseEventsTest.java
@@ -31,7 +31,6 @@ import org.bukkit.event.player.PlayerTeleportEvent;
 import org.bukkit.event.player.PlayerTeleportEvent.TeleportCause;
 import org.bukkit.inventory.ItemStack;
 import org.bukkit.inventory.PlayerInventory;
-import org.bukkit.util.BoundingBox;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
@@ -430,8 +429,7 @@ public class GreenhouseEventsTest {
      */
     @Test
     public void testOnBlockBreak() {
-        BoundingBox bb = BoundingBox.of(location, location2);
-        when(gh1.getBoundingBox()).thenReturn(bb);
+        when(gh1.isRoofOrWallBlock(any())).thenReturn(true);
         // Location is a wall block
         Block block = mock(Block.class);
         when(block.getLocation()).thenReturn(location);