diff --git a/meta/conf/machine/include/x86/qemuboot-x86.inc b/meta/conf/machine/include/x86/qemuboot-x86.inc
index dd7e7c9384..6ae03633ae 100644
--- a/meta/conf/machine/include/x86/qemuboot-x86.inc
+++ b/meta/conf/machine/include/x86/qemuboot-x86.inc
@@ -1,11 +1,11 @@
 # For runqemu
 IMAGE_CLASSES += "qemuboot"
 QB_SMP ?= "-smp 4"
-QB_CPU:x86 = "-cpu IvyBridge -machine q35,i8042=off"
-QB_CPU_KVM:x86 = "-cpu IvyBridge -machine q35,i8042=off"
+QB_CPU:x86 ?= "-cpu IvyBridge -machine q35,i8042=off"
+QB_CPU_KVM:x86 ?= "-cpu IvyBridge -machine q35,i8042=off"
 
-QB_CPU:x86-64 = "-cpu IvyBridge -machine q35,i8042=off"
-QB_CPU_KVM:x86-64 = "-cpu IvyBridge -machine q35,i8042=off"
+QB_CPU:x86-64 ?= "-cpu IvyBridge -machine q35,i8042=off"
+QB_CPU_KVM:x86-64 ?= "-cpu IvyBridge -machine q35,i8042=off"
 
 QB_AUDIO_DRV = "alsa"
 QB_AUDIO_OPT = "-device AC97"