diff --git a/libdasd/dasd_ioctl.c b/libdasd/dasd_ioctl.c
index 49d2cea9..f9549612 100644
--- a/libdasd/dasd_ioctl.c
+++ b/libdasd/dasd_ioctl.c
@@ -146,7 +146,7 @@ int dasd_is_ro(const char *device, bool *ro)
 {
 	int fd, val;
 
-	fd = dasd_open_device(device, O_RDWR);
+	fd = dasd_open_device(device, O_RDONLY);
 	RUN_IOCTL(fd, BLKROGET, &val);
 	*ro = (val != 0) ? true : false;
 	dasd_close_device(fd);