diff --git a/autoload/youcompleteme.vim b/autoload/youcompleteme.vim
index 3002e885..404b493a 100644
--- a/autoload/youcompleteme.vim
+++ b/autoload/youcompleteme.vim
@@ -370,6 +370,13 @@ function! s:OnCursorMovedInsertMode()
   if g:ycm_auto_trigger || s:omnifunc_mode
     call s:InvokeCompletion()
   endif
+
+  " We have to make sure we correctly leave omnifunc mode even when the user
+  " inserts something like a "operator[]" candidate string which fails
+  " CurrentIdentifierFinished check.
+  if s:omnifunc_mode && !pyeval( 'base.LastEnteredCharIsIdentifierChar()')
+    let s:omnifunc_mode = 0
+  endif
 endfunction
 
 
diff --git a/python/ycm/base.py b/python/ycm/base.py
index e578fa3b..2d0c2f7d 100644
--- a/python/ycm/base.py
+++ b/python/ycm/base.py
@@ -93,6 +93,20 @@ def CurrentIdentifierFinished():
     return line[ : current_column ].isspace()
 
 
+def LastEnteredCharIsIdentifierChar():
+  current_column = vimsupport.CurrentColumn()
+  previous_char_index = current_column - 1
+  if previous_char_index < 0:
+    return False
+  line = vim.current.line
+  try:
+    previous_char = line[ previous_char_index ]
+  except IndexError:
+    return False
+
+  return utils.IsIdentifierChar( previous_char )
+
+
 def AdjustCandidateInsertionText( candidates ):
   """This function adjusts the candidate insertion text to take into account the
   text that's currently in front of the cursor.