diff --git a/src/main.rs b/src/main.rs
index fdf51cdb6..3db8bfc34 100755
--- a/src/main.rs
+++ b/src/main.rs
@@ -79,7 +79,7 @@ fn main() {
         }
     }
 
-    let default_vcpus = format! {"{}", config::DEFAULT_VCPUS};
+    let default_vcpus = format! {"boot={}", config::DEFAULT_VCPUS};
     let default_memory = format! {"size={}M", config::DEFAULT_MEMORY_MB};
     let default_rng = format! {"src={}", config::DEFAULT_RNG_SOURCE};