diff --git a/lib/connection.js b/lib/connection.js
index 12c0b8bb12a..e28fb49d7ac 100644
--- a/lib/connection.js
+++ b/lib/connection.js
@@ -29,6 +29,7 @@ const Packets = require('./packets/index.js');
 const Commands = require('./commands/index.js');
 const ConnectionConfig = require('./connection_config.js');
 const CharsetToEncoding = require('./constants/charset_encodings.js');
+const ErrorCodeToName = require('./constants/errors.js');
 
 let _connectionId = 0;
 
@@ -405,10 +406,10 @@ class Connection extends EventEmitter {
 
     const err = new Error(message);
     err.fatal = true;
-    err.code = code || 'PROTOCOL_ERROR';
+    err.code = ErrorCodeToName[code] || 'PROTOCOL_ERROR';
     this.emit('error', err);
   }
-  
+
   get fatalError() {
     return this._fatalError;
   }
diff --git a/test/integration/test-server-close.js b/test/integration/test-server-close.js
index 23df672de24..fed1b9b0b10 100644
--- a/test/integration/test-server-close.js
+++ b/test/integration/test-server-close.js
@@ -40,5 +40,5 @@ process.on('uncaughtException', err => {
 
 process.on('exit', () => {
   assert.equal(error.message, 'The client was disconnected by the server because of inactivity. See wait_timeout and interactive_timeout for configuring this behavior.');
-  assert.equal(error.code, errors.ER_CLIENT_INTERACTION_TIMEOUT);
+  assert.equal(error.code, 'ER_CLIENT_INTERACTION_TIMEOUT');
 });