diff --git a/build/vnu-jar.js b/build/vnu-jar.js
index 77f9ed8489..22956cb7e9 100644
--- a/build/vnu-jar.js
+++ b/build/vnu-jar.js
@@ -13,10 +13,13 @@ const vnu = require('vnu-jar')
 
 execFile('java', ['-version'], (error, stdout, stderr) => {
   if (error) {
-    console.error('Skipping vnu-jar test; Java is missing.')
+    console.error('Skipping vnu-jar test; Java is probably missing.')
+    console.error(error)
     return
   }
 
+  console.log('Running vnu-jar validation...')
+
   const is32bitJava = !/64-Bit/.test(stderr)
 
   // vnu-jar accepts multiple ignores joined with a `|`.
@@ -48,6 +51,8 @@ execFile('java', ['-version'], (error, stdout, stderr) => {
     args.splice(0, 0, '-Xss512k')
   }
 
+  console.log(`command used: java ${args.join(' ')}`)
+
   return spawn('java', args, {
     shell: true,
     stdio: 'inherit'