diff --git a/tools/build_kvm.sh b/tools/build_kvm.sh
index 03a3877..dbfb5ce 100755
--- a/tools/build_kvm.sh
+++ b/tools/build_kvm.sh
@@ -101,8 +101,8 @@ function kill_unmount() {
     exit 1
 }
 
-# Install deps
-apt-get install -y --force-yes kvm libvirt-bin kpartx
+# Install deps if needed
+dpkg -l kvm libvirt-bin kpartx || apt-get install -y --force-yes kvm libvirt-bin kpartx
 
 # Let Ctrl-c kill tail and exit
 trap kill_unmount SIGINT