diff --git a/lib/logger/index.js b/lib/logger/index.js
index 1180429dd710242535fc271011518e614cf210cd..bcb37e83fccd1e75f179165733d6320e48102c1d 100644
--- a/lib/logger/index.js
+++ b/lib/logger/index.js
@@ -6,22 +6,25 @@ let bunyanLogger;
 let meta = {};
 
 function initLogger() {
-  const prettyStdOut = new PrettyStdout();
-  prettyStdOut.pipe(process.stdout);
+  const stdout = {
+    name: 'stdout',
+    level: process.env.LOG_LEVEL || 'info',
+    stream: process.stdout,
+  };
+
+  if (process.env.LOG_FORMAT !== 'json') {
+    const prettyStdOut = new PrettyStdout();
+    prettyStdOut.pipe(process.stdout);
+    stdout.type = 'raw';
+    stdout.stream = prettyStdOut;
+  }
 
   bunyanLogger = bunyan.createLogger({
     name: 'renovate',
     serializers: {
       config: configSerializer,
     },
-    streams: [
-      {
-        name: 'stdout',
-        level: process.env.LOG_LEVEL || 'info',
-        type: 'raw',
-        stream: prettyStdOut,
-      },
-    ],
+    streams: [stdout],
   });
 
   global.logger = {};