diff --git a/cmds-replace.c b/cmds-replace.c
index 186a127f..9fe7ad85 100644
--- a/cmds-replace.c
+++ b/cmds-replace.c
@@ -308,6 +308,11 @@ static int cmd_start_replace(int argc, char **argv)
 				"ERROR: ioctl(DEV_REPLACE_START) failed on \"%s\": %s, %s\n",
 				path, strerror(errno),
 				replace_dev_result2string(start_args.result));
+
+			if (errno == EOPNOTSUPP)
+				fprintf(stderr,
+					"WARNING: dev_replace does not yet handle RAID5/6\n");
+
 			goto leave_with_error;
 		}