diff --git a/python/ycm/completers/completer.py b/python/ycm/completers/completer.py
index efd8feff..780f1f78 100644
--- a/python/ycm/completers/completer.py
+++ b/python/ycm/completers/completer.py
@@ -242,7 +242,7 @@ class Completer( object ):
     return []
 
 
-  def GetDetailedDiagnostic( self ):
+  def GetDetailedDiagnostic( self, request_data ):
     pass