diff --git a/lib/winston/logger.js b/lib/winston/logger.js
index 5f8758c89..61a9fcb0f 100644
--- a/lib/winston/logger.js
+++ b/lib/winston/logger.js
@@ -141,6 +141,17 @@ class Logger extends Transform {
       );
     }
 
+    if (!Object.keys(this.levels).includes(this.level)) {
+      const message = [
+        '[winston] Log level <${this.level}> is not defined in levels definition.',
+        'Please double check the setup of your transports and/or custom log levels.',
+        'This transport will be set to silent.',
+        'See https://github.com/winstonjs/winston#logging-levels for more information.'
+      ].join('\n');
+      console.warn(message);
+      this.silent = true;
+    }
+
     if (exceptionHandlers) {
       this.exceptions.handle(exceptionHandlers);
     }