diff --git a/lib/iomap.c b/lib/iomap.c
index db004a9..dd6ca48 100644
--- a/lib/iomap.c
+++ b/lib/iomap.c
@@ -256,7 +256,7 @@
  * */
 void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
 {
-	unsigned long start = pci_resource_start(dev, bar);
+	resource_size_t start = pci_resource_start(dev, bar);
 	unsigned long len = pci_resource_len(dev, bar);
 	unsigned long flags = pci_resource_flags(dev, bar);