diff --git a/runtime/syntax/ampl.vim b/runtime/syntax/ampl.vim
index 7f4dfa9..99a683a 100644
--- a/runtime/syntax/ampl.vim
+++ b/runtime/syntax/ampl.vim
@@ -3,9 +3,8 @@
 " Last Change:  2003 May 11
 
 
-if version < 600
- syntax clear
-elseif exists("b:current_syntax")
+" quit when a syntax file was already loaded
+if exists("b:current_syntax")
  finish
 endif
 
@@ -115,33 +114,26 @@
 
 
 
-if version >= 508 || !exists("did_ampl_syntax_inits")
-  if version < 508
-    let did_ampl_syntax_inits = 1
-    command -nargs=+ HiLink hi link <args>
-  else
-    command -nargs=+ HiLink hi def link <args>
-  endif
+command -nargs=+ HiLink hi def link <args>
 
-  " The default methods for highlighting. Can be overridden later.
-  HiLink amplEntityKeyword	Keyword
-  HiLink amplType		Type
-  HiLink amplStatement		Statement
-  HiLink amplOperators		Operator
-  HiLink amplBasicOperators	Operator
-  HiLink amplConditional	Conditional
-  HiLink amplRepeat		Repeat
-  HiLink amplStrings		String
-  HiLink amplNumerics		Number
-  HiLink amplSetFunction	Function
-  HiLink amplBuiltInFunction	Function
-  HiLink amplRandomGenerator	Function
-  HiLink amplComment		Comment
-  HiLink amplDotSuffix		Special
-  HiLink amplPiecewise		Special
+" The default methods for highlighting. Can be overridden later.
+HiLink amplEntityKeyword	Keyword
+HiLink amplType		Type
+HiLink amplStatement		Statement
+HiLink amplOperators		Operator
+HiLink amplBasicOperators	Operator
+HiLink amplConditional	Conditional
+HiLink amplRepeat		Repeat
+HiLink amplStrings		String
+HiLink amplNumerics		Number
+HiLink amplSetFunction	Function
+HiLink amplBuiltInFunction	Function
+HiLink amplRandomGenerator	Function
+HiLink amplComment		Comment
+HiLink amplDotSuffix		Special
+HiLink amplPiecewise		Special
 
-  delcommand HiLink
-endif
+delcommand HiLink
 
 let b:current_syntax = "ampl"