diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -1582,6 +1582,21 @@ def debugwalk(ui, repo, *pats, **opts):
         line = fmt % (abs, m.rel(abs), m.exact(abs) and 'exact' or '')
         ui.write("%s\n" % line.rstrip())
 
+def debugwireargs(ui, repopath, *vals, **opts):
+    repo = hg.repository(hg.remoteui(ui, opts), repopath)
+    for opt in remoteopts:
+        del opts[opt[1]]
+    args = {}
+    for k, v in opts.iteritems():
+        if v:
+            args[k] = v
+    # run twice to check that we don't mess up the stream for the next command
+    res1 = repo.debugwireargs(*vals, **args)
+    res2 = repo.debugwireargs(*vals, **args)
+    ui.write("%s\n" % res1)
+    if res1 != res2:
+        ui.warn("%s\n" % res2)
+
 def diff(ui, repo, *pats, **opts):
     """diff repository (or selected files)
 
@@ -4456,6 +4471,12 @@ table = {
            _('revision to check'), _('REV'))],
          _('[-r REV] [REV]')),
     "debugwalk": (debugwalk, walkopts, _('[OPTION]... [FILE]...')),
+    "debugwireargs":
+        (debugwireargs,
+         [('', 'three', '', 'three'),
+          ('', 'four', '', 'four'),
+          ] + remoteopts,
+         _('REPO [OPTIONS]... [ONE [TWO]]')),
     "^diff":
         (diff,
          [('r', 'rev', [],
@@ -4789,6 +4810,6 @@ table = {
 }
 
 norepo = ("clone init version help debugcommands debugcomplete"
-          " debugdate debuginstall debugfsinfo debugpushkey")
+          " debugdate debuginstall debugfsinfo debugpushkey debugwireargs")
 optionalrepo = ("identify paths serve showconfig debugancestor debugdag"
                 " debugdata debugindex debugindexdot")
diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -1905,6 +1905,10 @@ class localrepository(repo.repository):
     def listkeys(self, namespace):
         return pushkey.list(self, namespace)
 
+    def debugwireargs(self, one, two, three=None, four=None):
+        '''used to test argument passing over the wire'''
+        return "%s %s %s %s" % (one, two, three, four)
+
 # used to avoid circular references so destructors work
 def aftertrans(files):
     renamefiles = [tuple(t) for t in files]
diff --git a/mercurial/wireproto.py b/mercurial/wireproto.py
--- a/mercurial/wireproto.py
+++ b/mercurial/wireproto.py
@@ -133,6 +133,15 @@ class wirerepository(repo.repository):
             self.ui.status(_('remote: '), l)
         return ret
 
+    def debugwireargs(self, one, two, three=None, four=None):
+        # don't pass optional arguments left at their default value
+        opts = {}
+        if three is not None:
+            opts['three'] = three
+        if four is not None:
+            opts['four'] = four
+        return self._call('debugwireargs', one=one, two=two, **opts)
+
 # server side
 
 class streamres(object):
@@ -199,6 +208,9 @@ def changegroupsubset(repo, proto, bases
     cg = repo.changegroupsubset(bases, heads, 'serve')
     return streamres(proto.groupchunks(cg))
 
+def debugwireargs(repo, proto, one, two):
+    return repo.debugwireargs(one, two)
+
 def heads(repo, proto):
     h = repo.heads()
     return encodelist(h) + "\n"
@@ -343,6 +355,7 @@ commands = {
     'capabilities': (capabilities, ''),
     'changegroup': (changegroup, 'roots'),
     'changegroupsubset': (changegroupsubset, 'bases heads'),
+    'debugwireargs': (debugwireargs, 'one two'),
     'heads': (heads, ''),
     'hello': (hello, ''),
     'listkeys': (listkeys, 'namespace'),
diff --git a/tests/test-debugcomplete.t b/tests/test-debugcomplete.t
--- a/tests/test-debugcomplete.t
+++ b/tests/test-debugcomplete.t
@@ -87,6 +87,7 @@ Show debug commands if there are no othe
   debugstate
   debugsub
   debugwalk
+  debugwireargs
 
 Do not show the alias of a debug command if there are other candidates
 (this should hide rawcommit)
@@ -227,6 +228,7 @@ Show all commands + options
   debugstate: nodates
   debugsub: rev
   debugwalk: include, exclude
+  debugwireargs: three, four, ssh, remotecmd, insecure
   grep: print0, all, follow, ignore-case, files-with-matches, line-number, rev, user, date, include, exclude
   heads: rev, topo, active, closed, style, template
   help: 
diff --git a/tests/test-wireproto.t b/tests/test-wireproto.t
new file mode 100644
--- /dev/null
+++ b/tests/test-wireproto.t
@@ -0,0 +1,42 @@
+
+Test wire protocol argument passing
+
+Setup repo:
+
+  $ hg init repo
+
+Local:
+
+  $ hg debugwireargs repo eins zwei
+  eins zwei None None
+
+HTTP:
+
+  $ hg serve -R repo -p $HGPORT -d --pid-file=hg1.pid -E error.log -A access.log
+  $ cat hg1.pid >> $DAEMON_PIDS
+
+  $ hg debugwireargs http://localhost:$HGPORT/ eins zwei
+  eins zwei None None
+  $ cat access.log
+  * - - [*] "GET /?cmd=capabilities HTTP/1.1" 200 - (glob)
+  * - - [*] "GET /?cmd=debugwireargs&one=eins&two=zwei HTTP/1.1" 200 - (glob)
+  * - - [*] "GET /?cmd=debugwireargs&one=eins&two=zwei HTTP/1.1" 200 - (glob)
+
+SSH (try to exercise the ssh functionality with a dummy script):
+
+  $ cat <<EOF > dummyssh
+  > import sys
+  > import os
+  > os.chdir(os.path.dirname(sys.argv[0]))
+  > if sys.argv[1] != "user@dummy":
+  >     sys.exit(-1)
+  > if not os.path.exists("dummyssh"):
+  >     sys.exit(-1)
+  > os.environ["SSH_CLIENT"] = "127.0.0.1 1 2"
+  > r = os.system(sys.argv[2])
+  > sys.exit(bool(r))
+  > EOF
+
+  $ hg debugwireargs --ssh "python ./dummyssh" ssh://user@dummy/repo eins zwei
+  eins zwei None None
+