diff --git a/spike/x86/cost.sh b/spike/x86/cost.sh
index 87b82e6..5b9b105 100755
--- a/spike/x86/cost.sh
+++ b/spike/x86/cost.sh
@@ -78,6 +78,10 @@ text () { size -A "$1" 2>/dev/null | awk '$1==".text" {print $2}'; }
 # Best of REPS, in whole microseconds. A program that fails on one run and
 # not another would make this meaningless, so the exit status of the first
 # run is remembered and a run that disagrees with it poisons the row as -1.
+# A program that hits the timeout is not timed at all: several of the corpus
+# programs are agents or daemons that sit waiting for something that is not
+# there, and five repetitions of a twenty-second wait, twice, is most of an
+# afternoon spent measuring `timeout`.
 best () {
   exe=$1; min=; rc0=
   for i in $(seq "$REPS"); do
@@ -88,6 +92,7 @@ best () {
     [ -n "$rc0" ] || rc0=$rc
     [ "$rc" = "$rc0" ] || { echo "-1"; return; }
     d=$(( (t1 - t0) / 1000 ))
+    [ "$d" -lt 15000000 ] || { echo "-1"; return; }
     if [ -z "$min" ] || [ "$d" -lt "$min" ]; then min=$d; fi
   done
   echo "$min"