--- a/src/monattack.cpp
+++ b/src/monattack.cpp
@@ -1450,9 +1450,12 @@
             continue;
         }
 
+        // 1 in 3 chance to terraform diggable terrain
         if( g->m.is_bashable( p ) && one_in( 3 ) ) {
-            // Destroy everything
-            g->m.destroy( p );
+            if( g->m.has_furn( p ) ) {
+                // Destroy any furniture
+                g->m.destroy_furn( p );
+            }
             // And then make the ground fertile
             g->m.ter_set( p, t_dirtmound );
             continue;