diff --git a/tools/build_libvirt.sh b/tools/build_libvirt.sh
index 3eb2ff8..5ae8fda 100755
--- a/tools/build_libvirt.sh
+++ b/tools/build_libvirt.sh
@@ -427,7 +427,7 @@
 
     kill $TAIL_PID
 
-    if grep -q "stack.sh failed" $VM_DIR/console.log; then
+    if ! grep -q "^stack.sh completed in" $VM_DIR/console.log; then
         exit 1
     fi
     echo ""