diff --git a/removeads.py b/removeads.py
index 206cf89..9ea5f1a 100755
--- a/removeads.py
+++ b/removeads.py
@@ -28,7 +28,7 @@ from shutil import copyfile, which
 def checkRequiredTools():
     logger = logging.getLogger(__name__)
     required = ['ffmpeg', 'ffprobe', 'mkvmerge']
-    optional = ['mkvextract', 'vobusbocr']
+    optional = ['mkvextract', 'vobsubocr']
     for tool in required:
         if which(tool) == None:
             logger.error('Required tool: %s is missing.' % tool)