diff --git a/runtime/syntax/j.vim b/runtime/syntax/j.vim
index bde9545..0cdd59b 100644
--- a/runtime/syntax/j.vim
+++ b/runtime/syntax/j.vim
@@ -2,7 +2,7 @@
 " Language:	J
 " Maintainer:	David Bürgin <676c7473@gmail.com>
 " URL:		https://github.com/glts/vim-j
-" Last Change:	2014-05-25
+" Last Change:	2014-10-05
 
 if exists('b:current_syntax')
   finish
@@ -12,7 +12,7 @@
 set cpo&vim
 
 syntax case match
-syntax sync minlines=50
+syntax sync minlines=100
 
 syntax cluster jStdlibItems contains=jStdlibNoun,jStdlibAdverb,jStdlibConjunction,jStdlibVerb
 syntax cluster jPrimitiveItems contains=jNoun,jAdverb,jConjunction,jVerb,jCopula
@@ -30,26 +30,32 @@
 syntax match jStdlibNoun /\<\%(adverb\|conjunction\|dyad\|monad\|noun\|verb\)\>/
 syntax match jStdlibVerb /\<\%(assert\|break\|do\)\>\.\@!/
 
-" Numbers. Matching J numbers is difficult. The regular expression used for
-" the general case roughly embodies this grammar sketch:
+" Numbers. Matching J numbers is difficult. In fact, the job cannot be done
+" with regular expressions alone. Below is a sketch of the pattern used. It
+" accepts most well-formed numbers and rejects most of the ill-formed ones.
+" See http://www.jsoftware.com/help/dictionary/dcons.htm for reference.
 "
-"     BASE     := /_?\d+(\.\d*)?([eE]_?\d+)?/
-"     RATIONAL := BASE  |  BASE r BASE
-"     COMPLEX  := BASE  |  BASE (j|a[dr]) BASE
-"     JNUMBER  := RATIONAL  |  RATIONAL [px] RATIONAL  |  COMPLEX  |  COMPLEX [px] COMPLEX
+" "double1" and "double2" patterns:
+"     (_?\d+(\.\d*)?|_\.\d+)([eE]_?\d+)?
+"     (_?\d+(\.\d*)?|_\.\d+|\.\d+)([eE]_?\d+)?
 "
-" The grammar is implemented as shown in this pseudo-regexp:
+" "rational1" and "rational2" patterns:
+"     \k<double1>(r\k<double2>)?|__?
+"     \k<double2>(r\k<double2>)?|__?
 "
-"        base         rational                       complex                       remainder
-"     /\< B  (  [r]B ([px]B([r]B)?)?  |  (j|a[dr])B ([px]B((j|a[dr])B)?)?  |  [px]B ((j|a[dr]|r)B)?  )?/
+" "complex1" and "complex2" patterns:
+"     \k<rational1>((j|a[dr])\k<rational2>)?
+"     \k<rational2>((j|a[dr])\k<rational2>)?
 "
-" All in all, a compromise between correctness and practicality had to be
-" made. See http://www.jsoftware.com/help/dictionary/dcons.htm for reference.
-syntax match jNumber /\<_\=\d\+\%(\.\d*\)\=\%([eE]_\=\d\+\)\=\%(\%(r_\=\d\+\%(\.\d*\)\=\%([eE]_\=\d\+\)\=\%([px]_\=\d\+\%(\.\d*\)\=\%([eE]_\=\d\+\)\=\%(r_\=\d\+\%(\.\d*\)\=\%([eE]_\=\d\+\)\=\)\=\)\=\)\|\%(\%(j\|a[dr]\)_\=\d\+\%(\.\d*\)\=\%([eE]_\=\d\+\)\=\%([px]_\=\d\+\%(\.\d*\)\=\%([eE]_\=\d\+\)\=\%(\%(j\|a[dr]\)_\=\d\+\%(\.\d*\)\=\%([eE]_\=\d\+\)\=\)\=\)\=\)\|\%([px]_\=\d\+\%(\.\d*\)\=\%([eE]_\=\d\+\)\=\%(\%(j\|a[dr]\|r\)_\=\d\+\%(\.\d*\)\=\%([eE]_\=\d\+\)\=\)\=\)\)\=/
-syntax match jNumber /\<_\=\d\+\%([eE]\d\+\)\=b_\=[0-9a-z]\+\%(\.[0-9a-z]\+\)\=/
-syntax match jNumber /\<__\=\>/
-syntax match jNumber /\<_\./
-syntax match jNumber /\<_\=\d\+x\>/
+" "basevalue" pattern:
+"     _?[0-9a-z]+(\.[0-9a-z]*)?|_?\.[0-9a-z]+
+"
+" all numbers:
+"     \b\k<complex1>([px]\k<complex2>)?(b\k<basevalue>)?(?![0-9A-Za-z_.])
+syntax match jNumber /\<_\.[0-9A-Za-z_.]\@!/
+syntax match jNumber /\<_\=\d\+x[0-9A-Za-z_.]\@!/
+syntax match jNumber /\<\%(__\=r_\=\d\+\|_\=\d\+r__\=\)[0-9A-Za-z_.]\@!/
+syntax match jNumber /\<\%(\%(_\=\d\+\%(\.\d*\)\=\|_\.\d\+\)\%([eE]_\=\d\+\)\=\%(r\%(_\=\d\+\%(\.\d*\)\=\|_\.\d\+\|\.\d\+\)\%([eE]_\=\d\+\)\=\)\=\|__\=\)\%(\%(j\|a[dr]\)\%(\%(_\=\d\+\%(\.\d*\)\=\|_\.\d\+\|\.\d\+\)\%([eE]_\=\d\+\)\=\%(r\%(_\=\d\+\%(\.\d*\)\=\|_\.\d\+\|\.\d\+\)\%([eE]_\=\d\+\)\=\)\=\|__\=\)\)\=\%([px]\%(\%(_\=\d\+\%(\.\d*\)\=\|_\.\d\+\|\.\d\+\)\%([eE]_\=\d\+\)\=\%(r\%(_\=\d\+\%(\.\d*\)\=\|_\.\d\+\|\.\d\+\)\%([eE]_\=\d\+\)\=\)\=\|__\=\)\%(\%(j\|a[dr]\)\%(\%(_\=\d\+\%(\.\d*\)\=\|_\.\d\+\|\.\d\+\)\%([eE]_\=\d\+\)\=\%(r\%(_\=\d\+\%(\.\d*\)\=\|_\.\d\+\|\.\d\+\)\%([eE]_\=\d\+\)\=\)\=\|__\=\)\)\=\)\=\%(b\%(_\=[0-9a-z]\+\%(\.[0-9a-z]*\)\=\|_\=\.[0-9a-z]\+\)\)\=[0-9A-Za-z_.]\@!/
 
 syntax region jString oneline start=/'/ skip=/''/ end=/'/
 
diff --git a/runtime/syntax/rst.vim b/runtime/syntax/rst.vim
index fce9e5d..c1f2569 100644
--- a/runtime/syntax/rst.vim
+++ b/runtime/syntax/rst.vim
@@ -1,8 +1,8 @@
 " Vim syntax file
-" Language:         reStructuredText documentation format
-" Maintainer:       Marshall Ward <marshall.ward@gmail.com>
+" Language: reStructuredText documentation format
+" Maintainer: Marshall Ward <marshall.ward@gmail.com>
 " Previous Maintainer: Nikolai Weibull <now@bitwi.se>
-" Latest Revision:  2014-08-23
+" Latest Revision: 2014-10-03
 
 if exists("b:current_syntax")
   finish
@@ -150,12 +150,19 @@
 
 for code in g:rst_syntax_code_list
     unlet! b:current_syntax
+    " guard against setting 'isk' option which might cause problems (issue #108)
+    let prior_isk = &l:iskeyword
     exe 'syn include @rst'.code.' syntax/'.code.'.vim'
     exe 'syn region rstDirective'.code.' matchgroup=rstDirective fold '
                 \.'start=#\%(sourcecode\|code\%(-block\)\=\)::\s\+'.code.'\_s*\n\ze\z(\s\+\)# '
                 \.'skip=#^$# '
                 \.'end=#^\z1\@!# contains=@NoSpell,@rst'.code
     exe 'syn cluster rstDirectives add=rstDirective'.code
+    " reset 'isk' setting, if it has been changed
+    if &l:iskeyword !=# prior_isk
+        let &l:iskeyword = prior_isk
+    endif
+    unlet! prior_isk
 endfor
 
 " TODO: Use better syncing.