diff --git a/start_qemu/start.sh b/start_qemu/start.sh
index 7129bd8..5c4ad8c 100644
--- a/start_qemu/start.sh
+++ b/start_qemu/start.sh
@@ -18,11 +18,11 @@ function createQcow2 {
 function checkQcow2 { if [ ! -f "$dir/$hda" ]; then createQcow2; fi }
 
 function bootCD {
-  qemu-system-x86_64 -enable-kvm -m $mem -cpu host -smp $nCores -machine type=pc,accel=kvm -boot d -cdrom $iso -hda $hda
+  qemu-system-x86_64 -enable-kvm -m $mem -cpu host -smp cpus=$nCores -machine type=pc,accel=kvm -boot d -cdrom $iso -hda $hda
 }
 
 function bootHD {
-  qemu-system-x86_64 -enable-kvm -m $mem -cpu host -smp $nCores -machine type=pc,accel=kvm -net nic,model=e1000 -hda $hda -net user
+  qemu-system-x86_64 -enable-kvm -m $mem -cpu host -smp cpus=$nCores -machine type=pc,accel=kvm -net nic,model=e1000 -hda $hda -net user
 }
 
 function showHelp {