diff --git a/types/bunyan/bunyan-tests.ts b/types/bunyan/bunyan-tests.ts
index 8b8f88a60c..d4c4f61e1c 100644
--- a/types/bunyan/bunyan-tests.ts
+++ b/types/bunyan/bunyan-tests.ts
@@ -130,5 +130,7 @@ class MyLogger extends Logger {
     }
 }
 
-const nameLevel: number = Logger.levelFromName['warn'];
+const logLevelString: Logger.LogLevelString = 'warn';
+const nameLevel: number = Logger.levelFromName[logLevelString];
+const nameLevel2: number = Logger.levelFromName['warn'];
 const levelName: string = Logger.nameFromLevel[10];
diff --git a/types/bunyan/index.d.ts b/types/bunyan/index.d.ts
index c622f7777d..a59790ebc9 100644
--- a/types/bunyan/index.d.ts
+++ b/types/bunyan/index.d.ts
@@ -2,6 +2,7 @@
 // Project: https://github.com/trentm/node-bunyan
 // Definitions by: Alex Mikhalev <https://github.com/amikhalev>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// TypeScript Version: 2.1
 
 /// <reference types="node" />
 
@@ -210,10 +211,11 @@ declare namespace Logger {
     const ERROR: number;
     const FATAL: number;
 
-    const levelFromName: { [name: string]: number };
-    const nameFromLevel: { [level: number]: string };
+    type LogLevelString = 'trace' | 'debug' | 'info' | 'warn' | 'error' | 'fatal';
+    type LogLevel = LogLevelString | number;
 
-    type LogLevel = 'trace' | 'debug' | 'info' | 'warn' | 'error' | 'fatal' | number;
+    const levelFromName: { [name in LogLevelString]: number };
+    const nameFromLevel: { [level: number]: string };
 
     const stdSerializers: StdSerializers;