diff --git a/sys/tools/makesyscalls.lua b/sys/tools/makesyscalls.lua
index 386a79e44eeb..e8f882f6641d 100644
--- a/sys/tools/makesyscalls.lua
+++ b/sys/tools/makesyscalls.lua
@@ -632,6 +632,7 @@ local function align_sysent_comment(col)
 end
 
 local function strip_arg_annotations(arg)
+	arg = arg:gsub("_Contains_[^ ]*[_)] ?", "")
 	arg = arg:gsub("_In[^ ]*[_)] ?", "")
 	arg = arg:gsub("_Out[^ ]*[_)] ?", "")
 	return trim(arg)