diff --git a/doc/fixes3-7-0.txt b/doc/fixes3-7-0.txt
index b2f4651bb..803596e42 100644
--- a/doc/fixes3-7-0.txt
+++ b/doc/fixes3-7-0.txt
@@ -1162,6 +1162,8 @@ prevent hug attacks and touch or engulf attacks for wrap, stick-to, and
 	vortices, a few others) or against worm tails
 wand of speed gives temporary speed, potion gives intrinsic
 some monsters (riders, shopkeepers, priests, quest leader) can break boulders
+if hero owes shop for a boulder and shopkeeper breaks it, continue to bill hero
+	for the boulder rather than switching to the resulting rocks
 corpse-eating monsters will go out of their way to eat corpses on the floor
 warnings via impossible() would be unseen if message suppression via ESC at
 	--More-- prompt was in effect
diff --git a/src/monmove.c b/src/monmove.c
index 5822d5fc9..19d2e70a7 100644
--- a/src/monmove.c
+++ b/src/monmove.c
@@ -159,6 +159,15 @@ m_break_boulder(struct monst *mtmp, coordxy x, coordxy y)
             set_msg_xy(x, y);
             pline_The("boulder falls apart.");
         }
+
+        /* boulders pushed onto shop's boundary or free spot are cases where
+           an item not in hero's inventory can have its unpaid flag set;
+           if the boulder isn't already on the bill, don't charge for it */
+        if (otmp->unpaid) {
+            /* remove original from bill and add cloned copy to used-up bill */
+            bill_dummy_object(otmp);
+        }
+        /* fracturing keeps otmp, changing its otyp from BOULDER to ROCK */
         fracture_rock(otmp);
     }
 }
diff --git a/src/zap.c b/src/zap.c
index e4ead85a6..6de9b7d59 100644
--- a/src/zap.c
+++ b/src/zap.c
@@ -5416,7 +5416,7 @@ mon_spell_hits_spot(
     }
 }
 
-/* fractured by pick-axe or wand of striking or by vault guard */
+/* fractured by pick-axe or wand of striking or by vault guard or shopkeeper */
 void
 fracture_rock(struct obj *obj) /* no texts here! */
 {