diff --git a/misc/vim/syntax/factor.vim b/misc/vim/syntax/factor.vim
index 2975545349..6c07265138 100644
--- a/misc/vim/syntax/factor.vim
+++ b/misc/vim/syntax/factor.vim
@@ -23,7 +23,7 @@ else
     set iskeyword=!,@,33-35,%,$,38-64,A-Z,91-96,a-z,123-126,128-255
 endif
 
-syn cluster factorCluster contains=factorComment,factorKeyword,factorRepeat,factorConditional,factorBoolean,factorCompileDirective,factorString,factorSbuf,@factorNumber,@factorNumErr,factorDelimiter,factorChar,factorCharErr,factorBackslash,@factorWordOps,factorAlien,factorTuple,factorStruct
+syn cluster factorCluster contains=factorComment,factorKeyword,factorRepeat,factorConditional,factorBoolean,factorCompileDirective,factorString,factorTriString,factorSbuf,@factorNumber,@factorNumErr,factorDelimiter,factorChar,factorCharErr,factorBackslash,@factorWordOps,factorAlien,factorTuple,factorStruct
 
 syn match factorTodo /\(TODO\|FIXME\|XXX\):\=/ contained
 syn match factorComment /\<#!\>.*/ contains=factorTodo