diff --git a/tests/head/head-c.sh b/tests/head/head-c.sh
index 750028564..0a9d311ac 100755
--- a/tests/head/head-c.sh
+++ b/tests/head/head-c.sh
@@ -39,7 +39,7 @@ esac
 # Only allocate memory as needed.
 # Coreutils <= 8.21 would allocate memory up front
 # based on the value passed to -c
-vm=$(get_min_ulimit_v_ head -c1 /dev/null) && {
+vm=$(get_min_ulimit_v_ head -c-1 /dev/null) && {
   (ulimit -v $(($vm+8000)) && head --bytes=-$SSIZE_MAX < /dev/null) || fail=1
   (ulimit -v $(($vm+8000)) &&
     head --bytes=-${UINTMAX_OFLOW}000 < /dev/null) || fail=1