diff --git a/NEWS b/NEWS
index a0283480..af985014 100644
--- a/NEWS
+++ b/NEWS
@@ -12,6 +12,7 @@ procps-ng-NEXT
   * top once again will fully honor a saved rcfile,
     without requiring --disable-modern-top. Debian #762928, #762947
   * vmstat: Not crash if partition appears before disk Debian #736628
+  * free: -s without -c works Debian #733758
 
 procps-ng-3.3.10
 ----------------
diff --git a/free.c b/free.c
index b19e07ff..6c72138c 100644
--- a/free.c
+++ b/free.c
@@ -323,6 +323,7 @@ int main(int argc, char **argv)
 			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);