diff --git a/src/testdir/test_syntax.vim b/src/testdir/test_syntax.vim
index 23ef154..43155d6 100644
--- a/src/testdir/test_syntax.vim
+++ b/src/testdir/test_syntax.vim
@@ -162,3 +162,134 @@
   call feedkeys(":syn match \<C-A>\<C-B>\"\<CR>", 'tx')
   call assert_match('^"syn match Boolean Character ', @:)
 endfunc
+
+func Test_syntax_arg_skipped()
+  syn clear
+  syntax case ignore
+  if 0
+    syntax case match
+  endif
+  call assert_match('case ignore', execute('syntax case'))
+
+  syn keyword Foo foo
+  call assert_match('Foo', execute('syntax'))
+  syn clear
+  call assert_match('case match', execute('syntax case'))
+  call assert_notmatch('Foo', execute('syntax'))
+
+  if has('conceal')
+    syn clear
+    syntax conceal on
+    if 0
+      syntax conceal off
+    endif
+    call assert_match('conceal on', execute('syntax conceal'))
+    syn clear
+    call assert_match('conceal off', execute('syntax conceal'))
+  endif
+
+  syntax region Tar start=/</ end=/>/
+  if 0
+    syntax region NotTest start=/</ end=/>/ contains=@Spell
+  endif
+  call assert_match('Tar', execute('syntax'))
+  call assert_notmatch('NotTest', execute('syntax'))
+  call assert_notmatch('Spell', execute('syntax'))
+
+  hi Foo ctermfg=blue
+  let a = execute('hi Foo')
+  if 0
+    syntax rest
+  endif
+  call assert_equal(a, execute('hi Foo'))
+
+  set ft=tags
+  syn off
+  if 0
+    syntax enable
+  endif
+  call assert_match('No Syntax items defined', execute('syntax'))
+  syntax enable
+  call assert_match('tagComment', execute('syntax'))
+  set ft=
+
+  syn clear
+  if 0
+    syntax include @Spell nothing
+  endif
+  call assert_notmatch('Spell', execute('syntax'))
+
+  syn clear
+  syn iskeyword 48-57,$,_
+  call assert_match('48-57,$,_', execute('syntax iskeyword'))
+  if 0
+    syn clear
+    syn iskeyword clear
+  endif
+  call assert_match('48-57,$,_', execute('syntax iskeyword'))
+  syn iskeyword clear
+  call assert_match('not set', execute('syntax iskeyword'))
+  syn iskeyword 48-57,$,_
+  syn clear
+  call assert_match('not set', execute('syntax iskeyword'))
+
+  syn clear
+  syn keyword Foo foo
+  if 0
+    syn keyword NotAdded bar
+  endif
+  call assert_match('Foo', execute('syntax'))
+  call assert_notmatch('NotAdded', execute('highlight'))
+
+  syn clear
+  syn keyword Foo foo
+  call assert_match('Foo', execute('syntax'))
+  call assert_match('Foo', execute('syntax list'))
+  call assert_notmatch('Foo', execute('if 0 | syntax | endif'))
+  call assert_notmatch('Foo', execute('if 0 | syntax list | endif'))
+
+  syn clear
+  syn match Fopi /asdf/
+  if 0
+    syn match Fopx /asdf/
+  endif
+  call assert_match('Fopi', execute('syntax'))
+  call assert_notmatch('Fopx', execute('syntax'))
+
+  syn clear
+  syn spell toplevel
+  call assert_match('spell toplevel', execute('syntax spell'))
+  if 0
+    syn spell notoplevel
+  endif
+  call assert_match('spell toplevel', execute('syntax spell'))
+  syn spell notoplevel
+  call assert_match('spell notoplevel', execute('syntax spell'))
+  syn spell default
+  call assert_match('spell default', execute('syntax spell'))
+
+  syn clear
+  if 0
+    syntax cluster Spell
+  endif
+  call assert_notmatch('Spell', execute('syntax'))
+
+  syn clear
+  syn keyword Foo foo
+  syn sync ccomment
+  syn sync maxlines=5
+  if 0
+    syn sync maxlines=11
+  endif
+  call assert_match('on C-style comments', execute('syntax sync'))
+  call assert_match('maximal 5 lines', execute('syntax sync'))
+  syn clear
+  syn keyword Foo foo
+  if 0
+    syn sync ccomment
+  endif
+  call assert_notmatch('on C-style comments', execute('syntax sync'))
+
+  syn clear
+endfunc
+