diff --git a/src/index.ts b/src/index.ts
index 157dc2c..52f4d87 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -11,7 +11,7 @@ export type LogColors = keyof typeof colors
 export interface LogEntry {
   timestamp: Date
   level: LogLevel
-  message: string
+  message: any
 }
 
 export class Logger {
@@ -60,7 +60,7 @@ export class Logger {
    * @example
    * logger.debug('no duplicates found, creating a document...')
    */
-  public debug(message: string, ...positionals: Array<unknown>): void {
+  public debug(message: any, ...positionals: Array<unknown>): void {
     this.logEntry({
       level: 'debug',
       message: colors.gray(message),
@@ -77,7 +77,7 @@ export class Logger {
    * @example
    * logger.info('start parsing...')
    */
-  public info(message: string, ...positionals: Array<unknown>) {
+  public info(message: any, ...positionals: Array<unknown>) {
     this.logEntry({
       level: 'info',
       message,
@@ -90,7 +90,7 @@ export class Logger {
 
     const performance = new PerformanceEntry()
 
-    return (message: string, ...positionals: Array<unknown>) => {
+    return (message: any, ...positionals: Array<unknown>) => {
       performance.measure()
 
       this.logEntry({
@@ -110,7 +110,7 @@ export class Logger {
    * @example
    * logger.success('successfully created document')
    */
-  public success(message: string, ...positionals: Array<unknown>): void {
+  public success(message: any, ...positionals: Array<unknown>): void {
     this.logEntry({
       level: 'info',
       message,
@@ -128,7 +128,7 @@ export class Logger {
    * @example
    * logger.warning('found legacy document format')
    */
-  public warning(message: string, ...positionals: Array<unknown>): void {
+  public warning(message: any, ...positionals: Array<unknown>): void {
     this.logEntry({
       level: 'warning',
       message,
@@ -146,7 +146,7 @@ export class Logger {
    * @example
    * logger.error('something went wrong')
    */
-  public error(message: string, ...positionals: Array<unknown>): void {
+  public error(message: any, ...positionals: Array<unknown>): void {
     this.logEntry({
       level: 'error',
       message,
@@ -172,7 +172,7 @@ export class Logger {
     callback()
   }
 
-  private createEntry(level: LogLevel, message: string): LogEntry {
+  private createEntry(level: LogLevel, message: unknown): LogEntry {
     return {
       timestamp: new Date(),
       level,
@@ -182,7 +182,7 @@ export class Logger {
 
   private logEntry(args: {
     level: LogLevel
-    message: string
+    message: unknown
     positionals?: Array<unknown>
     prefix?: string
     colors?: {
@@ -211,9 +211,9 @@ export class Logger {
     write(
       [colorize.timestamp(this.formatTimestamp(entry.timestamp))]
         .concat(prefix != null ? colorize.prefix(prefix) : [])
-        .concat(message)
+        .concat(serializeInput(message))
         .join(' '),
-      ...positionals
+      ...positionals.map(serializeInput)
     )
   }
 
@@ -304,3 +304,23 @@ function isDefinedAndNotEquals(
 ): boolean {
   return value !== undefined && value !== expected
 }
+
+function serializeInput(message: any): string {
+  if (typeof message === 'undefined') {
+    return 'undefined'
+  }
+
+  if (message === null) {
+    return 'null'
+  }
+
+  if (typeof message === 'string') {
+    return message
+  }
+
+  if (typeof message === 'object') {
+    return JSON.stringify(message)
+  }
+
+  return message.toString()
+}
diff --git a/test/node/Logger.test.ts b/test/node/Logger.test.ts
index 46f7b86..c36b85c 100644
--- a/test/node/Logger.test.ts
+++ b/test/node/Logger.test.ts
@@ -100,3 +100,19 @@ it('supports positionals', () => {
     `${colors.red('12:34:56:789')} ${colors.red('✖ [parser]')} hello world\n`
   )
 })
+
+it('serializes the input message', () => {
+  logger.info({ hello: 'world' })
+  expect(process.stdout.write).toHaveBeenCalledWith(
+    `${colors.gray('12:34:56:789')} ${colors.blue(
+      '[parser]'
+    )} {"hello":"world"}\n`
+  )
+
+  logger.info([1, 'two', { three: 3 }])
+  expect(process.stdout.write).toHaveBeenCalledWith(
+    `${colors.gray('12:34:56:789')} ${colors.blue(
+      '[parser]'
+    )} [1,"two",{"three":3}]\n`
+  )
+})