diff --git a/syntax/ats.vim b/syntax/ats.vim
index 14ed6b4..2953049 100644
--- a/syntax/ats.vim
+++ b/syntax/ats.vim
@@ -35,7 +35,7 @@ syn region atsArrow start="=<" end=">" contains=arrowContents
 syn region atsArrow start="-<" end=">"
 
 syn keyword atsType void bool string char int uint uint8 uint32 uint16 int8 int32 int16 charNZ strnptr Strptr0 Strptr1 nat lint ulint double float size_t
-syn keyword atsType datavtype datatype vtypedef dataviewtype viewtypdef typedef view viewdef dataview abstype absvtype absviewtype absview datasort dataprop type viewtype vtype
+syn keyword atsType datavtype datatype vtypedef dataviewtype viewtypdef typedef view viewdef dataview abstype absvtype absviewtype absview datasort dataprop type viewtype vtype propdef
 syn keyword atsType absimpl absprop
 syn keyword atsType implement primplmnt extern