diff --git a/b9.cabal b/b9.cabal
--- a/b9.cabal
+++ b/b9.cabal
@@ -1,5 +1,5 @@
 name:                b9
-version:             0.4.0
+version:             0.4.1
 
 synopsis:            A tool and library for building virtual machine images.
 
diff --git a/src/lib/B9/VmBuilder.hs b/src/lib/B9/VmBuilder.hs
--- a/src/lib/B9/VmBuilder.hs
+++ b/src/lib/B9/VmBuilder.hs
@@ -69,6 +69,7 @@
             -> FilePath
             -> VmScript
             -> B9 Bool
+runVmScript _ _ _ _ NoVmScript = return True
 runVmScript (IID iid) imageTargets buildImages instanceDir vmScript = do
   dbgL (printf "starting vm script with instanceDir '%s'" instanceDir)
   traceL (ppShow vmScript)