diff --git a/python/ycm/vimsupport.py b/python/ycm/vimsupport.py
index 2c39470d..8fd4a01a 100644
--- a/python/ycm/vimsupport.py
+++ b/python/ycm/vimsupport.py
@@ -103,7 +103,7 @@ def GetUnsavedAndCurrentBufferData():
 
 
 def GetBufferNumberForFilename( filename, open_file_if_needed = True ):
-  return GetIntValue( "bufnr('{0}', {1})".format(
+  return GetIntValue( u"bufnr('{0}', {1})".format(
       os.path.realpath( filename ),
       int( open_file_if_needed ) ) )