diff --git a/wally/suits/itest.py b/wally/suits/itest.py
index 259edf4..ed4e8c8 100644
--- a/wally/suits/itest.py
+++ b/wally/suits/itest.py
@@ -195,6 +195,9 @@
             except OSError:
                 need_install.append(package)
 
+        if len(need_install) == 0:
+            return
+
         cmd = "sudo apt-get -y install " + " ".join(need_install)
 
         for i in range(max_retry):