diff --git a/lib/logger.js b/lib/logger.js
index <HASH>..<HASH> 100644
--- a/lib/logger.js
+++ b/lib/logger.js
@@ -42,7 +42,11 @@ module.exports.setup = function(logs) {
 				Logger.emit('error', err)
 			})
 			stream.write = function(obj) {
-				dest.write(JSON.stringify(obj, Logger.safeCycles()) + '\n')
+				if (target.format === 'pretty') {
+					dest.write(print(obj.level, obj.msg, obj, false) + '\n')
+				} else {
+					dest.write(JSON.stringify(obj, Logger.safeCycles()) + '\n')
+				}
 			}
 		} else {
 			throw new Error('wrong target type for a log')
allow "pretty" format for logging into files

ref #<I>