diff --git a/drivers/block/rd.c b/drivers/block/rd.c
index 82f4eecc869..06e23be7090 100644
--- a/drivers/block/rd.c
+++ b/drivers/block/rd.c
@@ -56,6 +56,7 @@
 #include <linux/backing-dev.h>
 #include <linux/blkpg.h>
 #include <linux/writeback.h>
+#include <linux/log2.h>
 
 #include <asm/uaccess.h>
 
@@ -450,7 +451,7 @@ static int __init rd_init(void)
 	err = -ENOMEM;
 
 	if (rd_blocksize > PAGE_SIZE || rd_blocksize < 512 ||
-			(rd_blocksize & (rd_blocksize-1))) {
+			!is_power_of_2(rd_blocksize)) {
 		printk("RAMDISK: wrong blocksize %d, reverting to defaults\n",
 		       rd_blocksize);
 		rd_blocksize = BLOCK_SIZE;