diff --git a/drivers/net/dm9000.c b/drivers/net/dm9000.c
index 60de176..31b8bef 100644
--- a/drivers/net/dm9000.c
+++ b/drivers/net/dm9000.c
@@ -1251,8 +1251,6 @@
 #endif
 };
 
-#define res_size(_r) (((_r)->end - (_r)->start) + 1)
-
 /*
  * Search DM9000 board, allocate space and register it
  */
@@ -1301,7 +1299,7 @@
 		goto out;
 	}
 
-	iosize = res_size(db->addr_res);
+	iosize = resource_size(db->addr_res);
 	db->addr_req = request_mem_region(db->addr_res->start, iosize,
 					  pdev->name);
 
@@ -1319,7 +1317,7 @@
 		goto out;
 	}
 
-	iosize = res_size(db->data_res);
+	iosize = resource_size(db->data_res);
 	db->data_req = request_mem_region(db->data_res->start, iosize,
 					  pdev->name);