diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index ff7c87f..642cb4c 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -271,13 +271,12 @@
 					  unsigned long attrs)
 {
 	struct dma_map_ops *ops = get_dma_ops(dev);
-	unsigned long pfn = PHYS_PFN(phys_addr);
 	dma_addr_t addr;
 
 	BUG_ON(!valid_dma_direction(dir));
 
 	/* Don't allow RAM to be mapped */
-	BUG_ON(pfn_valid(pfn));
+	BUG_ON(pfn_valid(PHYS_PFN(phys_addr)));
 
 	addr = phys_addr;
 	if (ops->map_resource)