diff --git a/lib/winston/logger.js b/lib/winston/logger.js
index 0225183e5..febfb67f7 100644
--- a/lib/winston/logger.js
+++ b/lib/winston/logger.js
@@ -312,6 +312,7 @@ class Logger extends Transform {
     try {
       this.push(this.format.transform(info, this.format.options));
     } finally {
+      this._writableState.sync = false;
       // eslint-disable-next-line callback-return
       callback();
     }