diff --git a/include/haproxy/list.h b/include/haproxy/list.h
index c2fcdfbc6..95cc78a75 100644
--- a/include/haproxy/list.h
+++ b/include/haproxy/list.h
@@ -284,10 +284,11 @@ static __inline void watcher_attach(struct watcher *w, void *target)
 		MT_LIST_APPEND(list, &w->el);
 }
 
-/* Untracks target via <w> watcher. Invalid if <w> is not attached first. */
+/* Untracks target via <w> watcher. Does nothing if <w> is not attached */
 static __inline void watcher_detach(struct watcher *w)
 {
-	BUG_ON_HOT(!MT_LIST_INLIST(&w->el));
+	if (!MT_LIST_INLIST(&w->el))
+		return;
 	*w->pptr = NULL;
 	MT_LIST_DELETE(&w->el);
 }
diff --git a/src/hlua_fcn.c b/src/hlua_fcn.c
index cf8738e50..3e1cdef69 100644
--- a/src/hlua_fcn.c
+++ b/src/hlua_fcn.c
@@ -1913,6 +1913,21 @@ int hlua_listable_servers_pairs_iterator(lua_State *L)
 	return 2;
 }
 
+/* ensure proper cleanup for listable_servers_pairs */
+int hlua_listable_servers_pairs_gc(lua_State *L)
+{
+	struct hlua_server_list_iterator_context *ctx;
+
+	ctx = lua_touserdata(L, 1);
+
+	/* we need to make sure that the watcher leaves in detached state even
+	 * if the iterator was interrupted (ie: "break" from the loop), else
+	 * the server watcher list will become corrupted
+	 */
+	watcher_detach(&ctx->srv_watch);
+	return 0;
+}
+
 /* init the iterator context, return iterator function
  * with context as closure. The only argument is a
  * server list object.
@@ -1925,6 +1940,12 @@ int hlua_listable_servers_pairs(lua_State *L)
 	hlua_srv_list = hlua_check_server_list(L, 1);
 
 	ctx = lua_newuserdata(L, sizeof(*ctx));
+
+	/* add gc metamethod to the newly created userdata */
+	lua_newtable(L);
+	hlua_class_function(L, "__gc", hlua_listable_servers_pairs_gc);
+	lua_setmetatable(L, -2);
+
 	ctx->px = hlua_srv_list->px;
 	ctx->next = NULL;
 	watcher_init(&ctx->srv_watch, &ctx->next, offsetof(struct server, watcher_list));