diff --git a/lib/cli/cli.js b/lib/cli/cli.js
index ca2d720c0..0d5a563a9 100644
--- a/lib/cli/cli.js
+++ b/lib/cli/cli.js
@@ -38,7 +38,7 @@ try {
 } catch (e) {
   if (e instanceof SyntaxError) {
     console.error(
-      'Could not parse the config JSON file ' +
+      'Error: Could not parse the config JSON file ' +
         configPath +
         '. Is the file really valid JSON?'
     );
@@ -53,7 +53,7 @@ function validateInput(argv) {
   const majorVersion = fullVersion.split('.')[0];
   if (majorVersion < minVersion) {
     return (
-      'You need to have at least NodeJS version ' +
+      'Error: You need to have at least NodeJS version ' +
       minVersion +
       ' to run sitespeed.io. You are using version ' +
       fullVersion
@@ -61,19 +61,19 @@ function validateInput(argv) {
   }
 
   if (argv.headless && (argv.video || argv.visualMetrics)) {
-    return 'You cannot combine headless with video/visualMetrics because they need a screen to work.';
+    return 'Error: You cannot combine headless with video/visualMetrics because they need a screen to work.';
   }
 
   if (Array.isArray(argv.browsertime.iterations)) {
-    return 'Ooops you passed number of iterations twice, remove one of them and try again.';
+    return 'Error: Ooops you passed number of iterations twice, remove one of them and try again.';
   }
 
   if (Array.isArray(argv.browser)) {
-    return 'You can only run with one browser at a time.';
+    return 'Error: You can only run with one browser at a time.';
   }
 
   if (argv.crawler && argv.crawler.depth && argv.multi) {
-    return 'Crawl do not work running in multi mode.';
+    return 'Error: Crawl do not work running in multi mode.';
   }
 
   if (
@@ -81,7 +81,7 @@ function validateInput(argv) {
     argv._ &&
     cliUtil.getURLs(argv._).length !== toArray(argv.urlAlias).length
   ) {
-    return 'You have a miss match between number of alias and URLs.';
+    return 'Error: You have a miss match between number of alias and URLs.';
   }
 
   if (
@@ -89,7 +89,7 @@ function validateInput(argv) {
     argv._ &&
     cliUtil.getURLs(argv._).length !== toArray(argv.groupAlias).length
   ) {
-    return 'You have a miss match between number of alias for groups and URLs.';
+    return 'Error: You have a miss match between number of alias for groups and URLs.';
   }
 
   // validate URLs/files
@@ -100,7 +100,11 @@ function validateInput(argv) {
       try {
         fs.statSync(urlOrFile);
       } catch (e) {
-        return urlOrFile + ' does not exist, is the path to the file correct?';
+        return (
+          'Error: ' +
+          urlOrFile +
+          ' does not exist, is the path to the file correct?'
+        );
       }
     }
   }
@@ -112,13 +116,13 @@ function validateInput(argv) {
         tools => friendlynames[tools][m] && friendlynames[tools][m][k]
       )
     ) {
-      return 'Require summary page metrics to be from given array';
+      return 'Error: Require summary page metrics to be from given array';
     }
   }
 
   for (let metric of toArray(argv.html.summaryBoxes)) {
     if (htmlConfig.html.summaryBoxes.indexOf(metric) === -1) {
-      return `${metric} is not part of summary box metric.`;
+      return `Error: ${metric} is not part of summary box metric.`;
     }
   }
 
@@ -132,7 +136,9 @@ function validateInput(argv) {
       );
       argv.html.summaryBoxesThresholds = JSON.parse(box);
     } catch (e) {
-      return 'Could not read ' + argv.html.summaryBoxesThresholds + ' ' + e;
+      return (
+        'Error: Could not read ' + argv.html.summaryBoxesThresholds + ' ' + e
+      );
     }
   }