diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c
index f91fd51..d84e705 100644
--- a/fs/compat_ioctl.c
+++ b/fs/compat_ioctl.c
@@ -1800,7 +1800,7 @@
 /* just account for different alignment */
 static int compat_ioctl_preallocate(struct file *file, unsigned long arg)
 {
-	struct space_resv_32	__user *p32 = (void __user *)arg;
+	struct space_resv_32	__user *p32 = compat_ptr(arg);
 	struct space_resv	__user *p = compat_alloc_user_space(sizeof(*p));
 
 	if (copy_in_user(&p->l_type,	&p32->l_type,	sizeof(s16)) ||
@@ -2802,7 +2802,7 @@
 #else
 	case FS_IOC_RESVSP:
 	case FS_IOC_RESVSP64:
-		error = ioctl_preallocate(filp, (void __user *)arg);
+		error = ioctl_preallocate(filp, compat_ptr(arg));
 		goto out_fput;
 #endif