diff --git a/runtime/syntax/ruby.vim b/runtime/syntax/ruby.vim
index 13d6d9e..c951fcf 100644
--- a/runtime/syntax/ruby.vim
+++ b/runtime/syntax/ruby.vim
@@ -3,7 +3,7 @@
 " Maintainer:		Doug Kearns <dougkearns@gmail.com>
 " URL:			https://github.com/vim-ruby/vim-ruby
 " Release Coordinator:	Doug Kearns <dougkearns@gmail.com>
-" Last Change:		2021 Jun 06
+" Last Change:		2021 Nov 03
 " ----------------------------------------------------------------------------
 "
 " Previous Maintainer:	Mirko Nasato
@@ -66,7 +66,7 @@
 com! -nargs=* SynFold call s:run_syntax_fold(<q-args>)
 
 " Not-Top Cluster {{{1
-syn cluster rubyNotTop contains=@rubyCommentNotTop,@rubyStringNotTop,@rubyRegexpSpecial,@rubyDeclaration,@rubyExceptionHandler,@rubyClassOperator,rubyConditional,rubyModuleName,rubyClassName,rubySymbolDelimiter,rubyParentheses,@Spell
+syn cluster rubyNotTop contains=@rubyCommentNotTop,@rubyStringNotTop,@rubyRegexpSpecial,@rubyDeclaration,@rubyExceptionHandler,@rubyClassOperator,rubyConditional,rubyModuleName,rubyClassName,rubySymbolDelimiter,rubyDoubleQuoteSymbolDelimiter,rubySingleQuoteSymbolDelimiter,rubyParentheses,@Spell
 
 " Whitespace Errors {{{1
 if exists("ruby_space_errors")
@@ -364,6 +364,9 @@
   SynFold 'class'  syn region rubyClassBlock  start="\<class\>"  matchgroup=rubyClass  skip="\<end:"			       end="\<end\>" contains=ALLBUT,@rubyNotTop
   SynFold 'module' syn region rubyModuleBlock start="\<module\>" matchgroup=rubyModule skip="\<end:"			       end="\<end\>" contains=ALLBUT,@rubyNotTop
 
+  " endless def
+  syn match rubyDefine "\<def\s\+\ze[^[:space:];#(]\+\%(\s\+\|\s*(.*)\s*\)=" nextgroup=rubyMethodDeclaration skipwhite
+
   " modifiers
   syn match rubyLineContinuation    "\\$" nextgroup=@rubyModifier skipwhite skipnl
   syn match rubyConditionalModifier "\<\%(if\|unless\)\>"
@@ -430,9 +433,10 @@
 " Comments and Documentation {{{1
 syn match   rubySharpBang    "\%^#!.*" display
 syn keyword rubyTodo	     FIXME NOTE TODO OPTIMIZE HACK REVIEW XXX todo contained
-syn match   rubyEncoding     "[[:alnum:]-]\+" contained display
+syn match   rubyEncoding     "[[:alnum:]-_]\+" contained display
 syn match   rubyMagicComment "\c\%<3l#\s*\zs\%(coding\|encoding\):"					contained nextgroup=rubyEncoding skipwhite
 syn match   rubyMagicComment "\c\%<10l#\s*\zs\%(frozen_string_literal\|warn_indent\|warn_past_scope\):" contained nextgroup=rubyBoolean  skipwhite
+syn match   rubyMagicComment "\c\%<10l#\s*\zs\%(shareable_constant_value\):"				contained nextgroup=rubyEncoding  skipwhite
 syn match   rubyComment	     "#.*" contains=@rubyCommentSpecial,rubySpaceError,@Spell
 
 syn cluster rubyCommentSpecial contains=rubySharpBang,rubyTodo,rubyMagicComment
@@ -465,6 +469,10 @@
 syn match rubySymbol "\%(\w\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*[?!]\=::\@!"he=e-1 contained containedin=rubyBlockParameterList,rubyCurlyBlock
 syn match rubySymbol "[]})\"':]\@1<!\<\%(\h\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*[!?]\=:[[:space:],;]\@="he=e-1
 syn match rubySymbol "[[:space:],{(]\%(\h\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*[!?]\=:[[:space:],;]\@="hs=s+1,he=e-1
+syn match rubySingleQuoteSymbolDelimiter "'" contained
+syn match rubySymbol "'\%(\\.\|[^']\)*'::\@!"he=e-1 contains=rubyQuoteEscape,rubyBackslashEscape,rubySingleQuoteSymbolDelimiter
+syn match rubyDoubleQuoteSymbolDelimiter "\"" contained
+syn match rubySymbol "\"\%(\\.\|[^\"]\)*\"::\@!"he=e-1 contains=@rubyStringSpecial,rubyDoubleQuoteSymbolDelimiter
 
 " __END__ Directive {{{1
 SynFold '__END__' syn region rubyData matchgroup=rubyDataDirective start="^__END__$" end="\%$"
@@ -565,6 +573,8 @@
 hi def link rubyPercentRegexpDelimiter	rubyRegexpDelimiter
 hi def link rubyPercentStringDelimiter	rubyStringDelimiter
 hi def link rubyPercentSymbolDelimiter	rubySymbolDelimiter
+hi def link rubyDoubleQuoteSymbolDelimiter rubySymbolDelimiter
+hi def link rubySingleQuoteSymbolDelimiter rubySymbolDelimiter
 hi def link rubyRegexpDelimiter		rubyStringDelimiter
 hi def link rubySymbolDelimiter		rubySymbol
 hi def link rubyString			String