diff --git a/test/e2e/lib/vm.bash b/test/e2e/lib/vm.bash
index 0e1cfbd77..2d3f86c9b 100644
--- a/test/e2e/lib/vm.bash
+++ b/test/e2e/lib/vm.bash
@@ -115,7 +115,7 @@ vm-setup() {
     CPU=$(echo $VM_QEMU_CPUMEM | sed 's/MACHINE:.*CPU:-smp \([^|]*\).*/\1/g')
     MEM=$(echo $VM_QEMU_CPUMEM | sed 's/MACHINE:.*CPU:.*MEM:-m \([^|]*\).*/\1/g')
     EXTRA_ARGS=$(echo $VM_QEMU_CPUMEM | sed 's/MACHINE:.*CPU:.*MEM:.*EXTRA:\([^|]*\).*/\1/g')
-    EXTRA_ARGS+=", \"-monitor\", \"unix:monitor.sock,server,nowait\""
+    EXTRA_ARGS+="${EXTRA_ARGS:+,} \"-monitor\", \"unix:monitor.sock,server,nowait\""
 
     VM_MONITOR="(cd \"$output_dir\" && socat STDIO unix-connect:monitor.sock)"