diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 742055908656..f2461bf9243d 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1842,16 +1842,24 @@ static void adjust_bridge_window(struct pci_dev *bridge, struct resource *res,
 				 struct list_head *add_list,
 				 resource_size_t new_size)
 {
-	resource_size_t add_size;
+	resource_size_t add_size, size = resource_size(res);
 
 	if (res->parent)
 		return;
 
-	if (resource_size(res) >= new_size)
+	if (!new_size)
 		return;
 
-	add_size = new_size - resource_size(res);
-	pci_dbg(bridge, "bridge window %pR extended by %pa\n", res, &add_size);
+	if (new_size > size) {
+		add_size = new_size - size;
+		pci_dbg(bridge, "bridge window %pR extended by %pa\n", res,
+			&add_size);
+	} else if (new_size < size) {
+		add_size = size - new_size;
+		pci_dbg(bridge, "bridge window %pR shrunken by %pa\n", res,
+			&add_size);
+	}
+
 	res->end = res->start + new_size - 1;
 	remove_from_list(add_list, res);
 }