diff -Naur procps-ng-3.3.10.orig/free.c procps-ng-3.3.10/free.c

--- procps-ng-3.3.10.orig/free.c	2015-12-01 17:23:26.702968686 +0100

+++ procps-ng-3.3.10/free.c	2015-12-01 17:22:34.590529390 +0100

@@ -262,6 +262,7 @@

 			break;

 		case 's':

 			flags |= FREE_REPEAT;

+			errno = 0;

 			args.repeat_interval = (1000000 * strtof(optarg, &endptr));

 			if (errno || optarg == endptr || (endptr && *endptr))

 				xerrx(EXIT_FAILURE, _("seconds argument `%s' failed"), optarg);