diff --git a/gfxnvidia.c b/gfxnvidia.c
index d3ee14e..2a5c7ae 100644
--- a/gfxnvidia.c
+++ b/gfxnvidia.c
@@ -89,7 +89,7 @@
 	if (!dev)
 		return 1;
 
-	io_base_addr = pcidev_readbar(dev, PCI_BASE_ADDRESS_0);
+	uint32_t io_base_addr = pcidev_readbar(dev, PCI_BASE_ADDRESS_0);
 	if (!io_base_addr)
 		return 1;