diff --git a/boot/firmware_test.go b/boot/firmware_test.go
index 6e43458..9a95b5d 100644
--- a/boot/firmware_test.go
+++ b/boot/firmware_test.go
@@ -3,6 +3,7 @@
 package boot_test
 
 import (
+	"cmp"
 	"encoding/json"
 	"fmt"
 	"net"
@@ -115,13 +116,13 @@ func (p *probe) start(t *testing.T, variant string, gen bool, incoming, kernel,
 	args := []string{
 		"-L", p.firmware,
 		"-machine", "q35,sata=off,smbus=off",
-		"-accel", "kvm", "-cpu", orElse("host", cpu),
+		"-accel", "kvm", "-cpu", cmp.Or(cpu, "host"),
 		"-m", "2048", "-smp", "2",
 		"-nodefaults", "-display", "none", "-serial", "stdio", "-monitor", "none",
 		"-qmp", "unix:" + qmp + ",server=on,wait=off",
 		"-bios", p.bios[variant],
-		"-kernel", orElse(p.kernel, kernel),
-		"-initrd", orElse(p.initrd, initrd),
+		"-kernel", cmp.Or(kernel, p.kernel),
+		"-initrd", cmp.Or(initrd, p.initrd),
 		"-append", "console=ttyS0 quiet loglevel=3 pci=lastbus=0 no_timer_check " +
 			"tsc=reliable rcupdate.rcu_expedited=1 TERM=dumb rdinit=/init",
 	}
@@ -397,12 +398,3 @@ func pct(v []float64, p int) float64 {
 	x, _ := boot.Percentile(v, float64(p)/100)
 	return x
 }
-
-// orElse is the override or the default, and exists so that a probe varying one argument
-// of the machine line does not need a second copy of the whole line.
-func orElse(dflt, override string) string {
-	if override != "" {
-		return override
-	}
-	return dflt
-}
diff --git a/boot/fwstages_test.go b/boot/fwstages_test.go
index 63cc208..e69c22d 100644
--- a/boot/fwstages_test.go
+++ b/boot/fwstages_test.go
@@ -45,7 +45,7 @@ func TestFirmwareStages(t *testing.T) {
 	reps := envInt(t, "REPS", 10)
 	initrd := probeInitrd(t)
 
-	flags := strings.Fields(orElse("--cpus 1 --memory 512 --max-cpus 16 --max-memory 8192 --hotplug-disks 1", os.Getenv("FLAGS")))
+	flags := strings.Fields(cmp.Or(os.Getenv("FLAGS"), "--cpus 1 --memory 512 --max-cpus 16 --max-memory 8192 --hotplug-disks 1"))
 	flags = append([]string{"--disk", "-", "--initrd", initrd, "--console", "file:/dev/stdout"}, flags...)
 	cli := filepath.Join(out, "bin", "spin-machine")
 	type variant struct {
diff --git a/boot/initcalls_test.go b/boot/initcalls_test.go
index 81b1b11..ffbdf66 100644
--- a/boot/initcalls_test.go
+++ b/boot/initcalls_test.go
@@ -3,12 +3,12 @@
 package boot_test
 
 import (
+	"cmp"
 	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"regexp"
-	"slices"
 	"sort"
 	"strconv"
 	"strings"
@@ -111,7 +111,7 @@ WantedBy=multi-user.target
 		checkName = name
 	}
 	dump = strings.Replace(dump, "FORMATCHECK ", check+" ", 1)
-	cvs := slices.Clone(cmdlineVariants)
+	cvs := []cmdlineVariant{{label: "baseline"}}
 	if k := kernelB(t); k != "" {
 		cvs = append(cvs, cmdlineVariant{label: "kernel B", kernel: k})
 	}
@@ -128,8 +128,8 @@ WantedBy=multi-user.target
 	}
 
 	base := variant{
-		cpus:   orElse("2", os.Getenv("CPUS")),
-		memory: orElse("2048", os.Getenv("MEMORY_MIB")),
+		cpus:   cmp.Or(os.Getenv("CPUS"), "2"),
+		memory: cmp.Or(os.Getenv("MEMORY_MIB"), "2048"),
 		flags:  strings.Fields(os.Getenv("FLAGS")),
 		files: map[string]string{
 			"/etc/systemd/system/spin-dmesg.service": dump,
@@ -282,7 +282,7 @@ func clip(s string) string {
 }
 
 // The command lines to compare: the baseline, which the per-initcall table below is taken
-// from, and a kernel B or C when one is named.
+// from, and a kernel B or C, or a command line B, when one is named.
 //
 // Smaller TCP and UDP hash tables (thash_entries=2048 uhash_entries=2048), for inet_init's
 // 8 ms on a machine that will never hold 32768 connections, moved nothing: 85.8 ms against
@@ -290,10 +290,6 @@ func clip(s string) string {
 // 30 boots, 2026-09-30).
 type cmdlineVariant struct{ label, extra, kernel string }
 
-var cmdlineVariants = []cmdlineVariant{
-	{label: "baseline"},
-}
-
 // initcallsOfInterest are printed side by side for every variant, because a variant that
 // moved the total is only interesting once it is clear which initcall moved.
 var initcallsOfInterest = []string{