diff --git a/runtime/syntax/prolog.vim b/runtime/syntax/prolog.vim
index 58de71f..f5f0e67 100644
--- a/runtime/syntax/prolog.vim
+++ b/runtime/syntax/prolog.vim
@@ -1,8 +1,8 @@
 " Vim syntax file
 " Language:    PROLOG
 " Maintainers: Thomas Koehler <jean-luc@picard.franken.de>
-" Last Change: 2009 Dec 04
-" URL:	       http://gott-gehabt.de/800_wer_wir_sind/thomas/Homepage/Computer/vim/syntax/prolog.vim
+" Last Change: 2013 May 23
+" URL:         http://gott-gehabt.de/800_wer_wir_sind/thomas/Homepage/Computer/vim/syntax/prolog.vim
 
 " There are two sets of highlighting in here:
 " If the "prolog_highlighting_clean" variable exists, it is rather sparse.
@@ -21,14 +21,14 @@
 " Very simple highlighting for comments, clause heads and
 " character codes.  It respects prolog strings and atoms.
 
-syn region   prologCComment	start=+/\*+ end=+\*/+
-syn match    prologComment	+%.*+
+syn region   prologCComment start=+/\*+ end=+\*/+
+syn match    prologComment  +%.*+
 
-syn keyword  prologKeyword	module meta_predicate multifile dynamic
-syn match    prologCharCode	+0'\\\=.+
-syn region   prologString      start=+"+ skip=+\\\\\|\\"+ end=+"+
-syn region   prologAtom                start=+'+ skip=+\\\\\|\\'+ end=+'+
-syn region   prologClauseHead   start=+^[a-z][^(]*(+ skip=+\.[^		]+ end=+:-\|\.$\|\.[	 ]\|-->+ contains=prologComment,prologCComment,prologString
+syn keyword  prologKeyword  module meta_predicate multifile dynamic
+syn match    prologCharCode +0'\\\=.+
+syn region   prologString   start=+"+ skip=+\\\\\|\\"+ end=+"+
+syn region   prologAtom     start=+'+ skip=+\\\\\|\\'+ end=+'+
+syn region   prologClause   matchgroup=prologClauseHead start=+^\s*[a-z]\w*+ matchgroup=Normal end=+\.\s\|\.$+ contains=ALLBUT,prologClause
 
 if !exists("prolog_highlighting_clean")
 
@@ -40,12 +40,12 @@
   syn keyword prologKeyword   arg     current_prolog_flag     put_char
   syn keyword prologKeyword   asserta fail    put_code
   syn keyword prologKeyword   assertz findall read
-  syn keyword prologKeyword   at_end_of_stream	      float   read_term
+  syn keyword prologKeyword   at_end_of_stream        float   read_term
   syn keyword prologKeyword   atom    flush_output    repeat
   syn keyword prologKeyword   atom_chars      functor retract
-  syn keyword prologKeyword   atom_codes      get_byte	      set_input
-  syn keyword prologKeyword   atom_concat     get_char	      set_output
-  syn keyword prologKeyword   atom_length     get_code	      set_prolog_flag
+  syn keyword prologKeyword   atom_codes      get_byte        set_input
+  syn keyword prologKeyword   atom_concat     get_char        set_output
+  syn keyword prologKeyword   atom_length     get_code        set_prolog_flag
   syn keyword prologKeyword   atomic  halt    set_stream_position
   syn keyword prologKeyword   bagof   integer setof
   syn keyword prologKeyword   call    is      stream_property
@@ -54,7 +54,7 @@
   syn keyword prologKeyword   char_conversion number  true
   syn keyword prologKeyword   clause  number_chars    unify_with_occurs_check
   syn keyword prologKeyword   close   number_codes    var
-  syn keyword prologKeyword   compound	      once    write
+  syn keyword prologKeyword   compound        once    write
   syn keyword prologKeyword   copy_term       op      write_canonical
   syn keyword prologKeyword   current_char_conversion open    write_term
   syn keyword prologKeyword   current_input   peek_byte       writeq
@@ -63,11 +63,13 @@
   syn match   prologOperator "=\\=\|=:=\|\\==\|=<\|==\|>=\|\\=\|\\+\|<\|>\|="
   syn match   prologAsIs     "===\|\\===\|<=\|=>"
 
-  syn match   prologNumber	      "\<[0123456789]*\>'\@!"
+  syn match   prologNumber            "\<[0123456789]*\>'\@!"
   syn match   prologCommentError      "\*/"
   syn match   prologSpecialCharacter  ";"
   syn match   prologSpecialCharacter  "!"
-  syn match   prologQuestion	      "?-.*\."	contains=prologNumber
+  syn match   prologSpecialCharacter  ":-"
+  syn match   prologSpecialCharacter  "-->"
+  syn match   prologQuestion          "?-.*\."  contains=prologNumber
 
 
 endif
@@ -87,27 +89,29 @@
   endif
 
   " The default highlighting.
-  HiLink prologComment		Comment
-  HiLink prologCComment		Comment
-  HiLink prologCharCode		Special
+  HiLink prologComment          Comment
+  HiLink prologCComment         Comment
+  HiLink prologCharCode         Special
 
   if exists ("prolog_highlighting_clean")
 
-    HiLink prologKeyword	Statement
-    HiLink prologClauseHead	Statement
+    HiLink prologKeyword        Statement
+    HiLink prologClauseHead     Statement
+    HiLink prologClause Normal
 
   else
 
-    HiLink prologKeyword	Keyword
-    HiLink prologClauseHead	Constant
-    HiLink prologQuestion	PreProc
+    HiLink prologKeyword        Keyword
+    HiLink prologClauseHead     Constant
+    HiLink prologClause Normal
+    HiLink prologQuestion       PreProc
     HiLink prologSpecialCharacter Special
-    HiLink prologNumber		Number
-    HiLink prologAsIs		Normal
-    HiLink prologCommentError	Error
-    HiLink prologAtom		String
-    HiLink prologString		String
-    HiLink prologOperator	Operator
+    HiLink prologNumber         Number
+    HiLink prologAsIs           Normal
+    HiLink prologCommentError   Error
+    HiLink prologAtom           String
+    HiLink prologString         String
+    HiLink prologOperator       Operator
 
   endif