diff --git a/hgext/win32text.py b/hgext/win32text.py
--- a/hgext/win32text.py
+++ b/hgext/win32text.py
@@ -1,4 +1,4 @@
-# win32text.py - LF <-> CRLF translation utilities for Windows users
+# win32text.py - LF <-> CRLF/CR translation utilities for Windows/Mac users
 #
 # This software may be used and distributed according to the terms
 # of the GNU General Public License, incorporated herein by reference.
@@ -9,18 +9,23 @@
 # hgext.win32text =
 # [encode]
 # ** = cleverencode:
+# # or ** = macencode:
 # [decode]
 # ** = cleverdecode:
+# # or ** = macdecode:
 #
-# If not doing conversion, to make sure you do not commit CRLF by accident:
+# If not doing conversion, to make sure you do not commit CRLF/CR by accident:
 #
 # [hooks]
 # pretxncommit.crlf = python:hgext.win32text.forbidcrlf
+# # or pretxncommit.cr = python:hgext.win32text.forbidcr
 #
-# To do the same check on a server to prevent CRLF from being pushed or pulled:
+# To do the same check on a server to prevent CRLF/CR from being pushed or
+# pulled:
 #
 # [hooks]
 # pretxnchangegroup.crlf = python:hgext.win32text.forbidcrlf
+# # or pretxnchangegroup.cr = python:hgext.win32text.forbidcr
 
 from mercurial import util
 from mercurial.i18n import gettext as _
@@ -30,23 +35,36 @@ import re
 # regexp for single LF without CR preceding.
 re_single_lf = re.compile('(^|[^\r])\n', re.MULTILINE)
 
-def dumbdecode(s, cmd, ui=None, repo=None, filename=None, **kwargs):
-    # warn if already has CRLF in repository.
+newlinestr = {'\r\n': 'CRLF', '\r': 'CR'}
+filterstr = {'\r\n': 'clever', '\r': 'mac'}
+
+def checknewline(s, newline, ui=None, repo=None, filename=None):
+    # warn if already has 'newline' in repository.
     # it might cause unexpected eol conversion.
     # see issue 302:
     #   http://www.selenic.com/mercurial/bts/issue302
-    if '\r\n' in s and ui and filename and repo:
-        ui.warn(_('WARNING: %s already has CRLF line endings\n'
+    if newline in s and ui and filename and repo:
+        ui.warn(_('WARNING: %s already has %s line endings\n'
                   'and does not need EOL conversion by the win32text plugin.\n'
                   'Before your next commit, please reconsider your '
                   'encode/decode settings in \nMercurial.ini or %s.\n') %
-                (filename, repo.join('hgrc')))
+                (filename, newlinestr[newline], repo.join('hgrc')))
+
+def dumbdecode(s, cmd, **kwargs):
+    checknewline(s, '\r\n', **kwargs)
     # replace single LF to CRLF
     return re_single_lf.sub('\\1\r\n', s)
 
 def dumbencode(s, cmd):
     return s.replace('\r\n', '\n')
 
+def macdumbdecode(s, cmd, **kwargs):
+    checknewline(s, '\r', **kwargs)
+    return s.replace('\n', '\r')
+
+def macdumbencode(s, cmd):
+    return s.replace('\r', '\n')
+
 def cleverdecode(s, cmd, **kwargs):
     if util.binary(s):
         return s
@@ -57,14 +75,28 @@ def cleverencode(s, cmd):
         return s
     return dumbencode(s, cmd)
 
+def macdecode(s, cmd, **kwargs):
+    if util.binary(s):
+        return s
+    return macdumbdecode(s, cmd, **kwargs)
+
+def macencode(s, cmd):
+    if util.binary(s):
+        return s
+    return macdumbencode(s, cmd)
+
 _filters = {
     'dumbdecode:': dumbdecode,
     'dumbencode:': dumbencode,
     'cleverdecode:': cleverdecode,
     'cleverencode:': cleverencode,
+    'macdumbdecode:': macdumbdecode,
+    'macdumbencode:': macdumbencode,
+    'macdecode:': macdecode,
+    'macencode:': macencode,
     }
 
-def forbidcrlf(ui, repo, hooktype, node, **kwargs):
+def forbidcrlforcr(ui, repo, hooktype, node, newline, **kwargs):
     halt = False
     for rev in xrange(repo.changelog.rev(bin(node)), repo.changelog.count()):
         c = repo.changectx(rev)
@@ -72,29 +104,38 @@ def forbidcrlf(ui, repo, hooktype, node,
             if f not in c:
                 continue
             data = c[f].data()
-            if not util.binary(data) and '\r\n' in data:
+            if not util.binary(data) and newline in data:
                 if not halt:
                     ui.warn(_('Attempt to commit or push text file(s) '
-                              'using CRLF line endings\n'))
+                              'using %s line endings\n') %
+                              newlinestr[newline])
                 ui.warn(_('in %s: %s\n') % (short(c.node()), f))
                 halt = True
     if halt and hooktype == 'pretxnchangegroup':
+        crlf = newlinestr[newline].lower()
+        filter = filterstr[newline]
         ui.warn(_('\nTo prevent this mistake in your local repository,\n'
                   'add to Mercurial.ini or .hg/hgrc:\n'
                   '\n'
                   '[hooks]\n'
-                  'pretxncommit.crlf = python:hgext.win32text.forbidcrlf\n'
+                  'pretxncommit.%s = python:hgext.win32text.forbid%s\n'
                   '\n'
                   'and also consider adding:\n'
                   '\n'
                   '[extensions]\n'
                   'hgext.win32text =\n'
                   '[encode]\n'
-                  '** = cleverencode:\n'
+                  '** = %sencode:\n'
                   '[decode]\n'
-                  '** = cleverdecode:\n'))
+                  '** = %sdecode:\n') % (crlf, crlf, filter, filter))
     return halt
 
+def forbidcrlf(ui, repo, hooktype, node, **kwargs):
+    return forbidcrlforcr(ui, repo, hooktype, node, '\r\n', **kwargs)
+
+def forbidcr(ui, repo, hooktype, node, **kwargs):
+    return forbidcrlforcr(ui, repo, hooktype, node, '\r', **kwargs)
+
 def reposetup(ui, repo):
     if not repo.local():
         return
diff --git a/tests/test-mactext b/tests/test-mactext
new file mode 100755
--- /dev/null
+++ b/tests/test-mactext
@@ -0,0 +1,115 @@
+#!/bin/sh
+
+cat > unix2mac.py <<EOF
+import sys
+
+for path in sys.argv[1:]:
+    data = file(path, 'rb').read()
+    data = data.replace('\n', '\r')
+    file(path, 'wb').write(data)
+EOF
+
+cat > print.py <<EOF
+import sys
+print(sys.stdin.read().replace('\n', '<LF>').replace('\r', '<CR>').replace('\0', '<NUL>'))
+EOF
+
+hg init
+echo '[hooks]' >> .hg/hgrc
+echo 'pretxncommit.cr = python:hgext.win32text.forbidcr' >> .hg/hgrc
+echo 'pretxnchangegroup.cr = python:hgext.win32text.forbidcr' >> .hg/hgrc
+cat .hg/hgrc
+echo
+
+echo hello > f
+hg add f
+hg ci -m 1 -d'0 0'
+echo
+
+python unix2mac.py f
+hg ci -m 2 -d'0 0'
+hg revert -a
+echo
+
+mkdir d
+echo hello > d/f2
+python unix2mac.py d/f2
+hg add d/f2
+hg ci -m 3 -d'0 0'
+hg revert -a
+rm d/f2
+echo
+
+hg rem f
+hg ci -m 4 -d'0 0'
+echo
+
+python -c 'file("bin", "wb").write("hello\x00\x0D")'
+hg add bin
+hg ci -m 5 -d'0 0'
+hg log -v
+echo
+
+hg clone . dupe
+echo
+for x in a b c d; do echo content > dupe/$x; done
+hg -R dupe add
+python unix2mac.py dupe/b dupe/c dupe/d
+hg -R dupe ci -m a -d'0 0' dupe/a
+hg -R dupe ci -m b/c -d'0 0' dupe/[bc]
+hg -R dupe ci -m d -d'0 0' dupe/d
+hg -R dupe log -v
+echo
+
+hg pull dupe
+echo
+
+hg log -v
+echo
+
+rm .hg/hgrc
+(echo some; echo text) > f3
+python -c 'file("f4.bat", "wb").write("rem empty\x0D")'
+hg add f3 f4.bat
+hg ci -m 6 -d'0 0'
+
+python print.py < bin
+python print.py < f3
+python print.py < f4.bat
+echo
+
+echo '[extensions]' >> .hg/hgrc
+echo 'win32text = ' >> .hg/hgrc
+echo '[decode]' >> .hg/hgrc
+echo '** = macdecode:' >> .hg/hgrc
+echo '[encode]' >> .hg/hgrc
+echo '** = macencode:' >> .hg/hgrc
+cat .hg/hgrc
+echo
+
+rm f3 f4.bat bin
+hg co 2>&1 | python -c 'import sys, os; sys.stdout.write(sys.stdin.read().replace(os.getcwd(), "...."))'
+python print.py < bin
+python print.py < f3
+python print.py < f4.bat
+echo
+
+python -c 'file("f5.sh", "wb").write("# empty\x0D")'
+hg add f5.sh
+hg ci -m 7 -d'0 0'
+python print.py < f5.sh
+hg cat f5.sh | python print.py
+
+echo '% just linefeed' > linefeed
+hg ci -qAm 8 linefeed
+python print.py < linefeed
+hg cat linefeed | python print.py
+hg st -q
+hg revert -a linefeed
+python print.py < linefeed
+hg st -q
+echo modified >> linefeed
+hg st -q
+hg revert -a
+hg st -q
+python print.py < linefeed
diff --git a/tests/test-mactext.out b/tests/test-mactext.out
new file mode 100644
--- /dev/null
+++ b/tests/test-mactext.out
@@ -0,0 +1,187 @@
+[hooks]
+pretxncommit.cr = python:hgext.win32text.forbidcr
+pretxnchangegroup.cr = python:hgext.win32text.forbidcr
+
+
+Attempt to commit or push text file(s) using CR line endings
+in dea860dc51ec: f
+transaction abort!
+rollback completed
+abort: pretxncommit.cr hook failed
+reverting f
+
+Attempt to commit or push text file(s) using CR line endings
+in 8aa1d87b4e2f: d/f2
+transaction abort!
+rollback completed
+abort: pretxncommit.cr hook failed
+forgetting d/f2
+
+
+changeset:   2:d7599e43717c
+tag:         tip
+user:        test
+date:        Thu Jan 01 00:00:00 1970 +0000
+files:       bin
+description:
+5
+
+
+changeset:   1:c72a7d1d0907
+user:        test
+date:        Thu Jan 01 00:00:00 1970 +0000
+files:       f
+description:
+4
+
+
+changeset:   0:fcf06d5c4e1d
+user:        test
+date:        Thu Jan 01 00:00:00 1970 +0000
+files:       f
+description:
+1
+
+
+
+updating working directory
+1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+
+adding dupe/a
+adding dupe/b
+adding dupe/c
+adding dupe/d
+changeset:   5:ebbcbe52b20e
+tag:         tip
+user:        test
+date:        Thu Jan 01 00:00:00 1970 +0000
+files:       d
+description:
+d
+
+
+changeset:   4:ceeb93d6508a
+user:        test
+date:        Thu Jan 01 00:00:00 1970 +0000
+files:       b c
+description:
+b/c
+
+
+changeset:   3:c5404edbb872
+user:        test
+date:        Thu Jan 01 00:00:00 1970 +0000
+files:       a
+description:
+a
+
+
+changeset:   2:d7599e43717c
+user:        test
+date:        Thu Jan 01 00:00:00 1970 +0000
+files:       bin
+description:
+5
+
+
+changeset:   1:c72a7d1d0907
+user:        test
+date:        Thu Jan 01 00:00:00 1970 +0000
+files:       f
+description:
+4
+
+
+changeset:   0:fcf06d5c4e1d
+user:        test
+date:        Thu Jan 01 00:00:00 1970 +0000
+files:       f
+description:
+1
+
+
+
+pulling from dupe
+searching for changes
+adding changesets
+adding manifests
+adding file changes
+added 3 changesets with 4 changes to 4 files
+Attempt to commit or push text file(s) using CR line endings
+in ceeb93d6508a: b
+in ceeb93d6508a: c
+in ebbcbe52b20e: d
+
+To prevent this mistake in your local repository,
+add to Mercurial.ini or .hg/hgrc:
+
+[hooks]
+pretxncommit.cr = python:hgext.win32text.forbidcr
+
+and also consider adding:
+
+[extensions]
+hgext.win32text =
+[encode]
+** = macencode:
+[decode]
+** = macdecode:
+transaction abort!
+rollback completed
+abort: pretxnchangegroup.cr hook failed
+
+changeset:   2:d7599e43717c
+tag:         tip
+user:        test
+date:        Thu Jan 01 00:00:00 1970 +0000
+files:       bin
+description:
+5
+
+
+changeset:   1:c72a7d1d0907
+user:        test
+date:        Thu Jan 01 00:00:00 1970 +0000
+files:       f
+description:
+4
+
+
+changeset:   0:fcf06d5c4e1d
+user:        test
+date:        Thu Jan 01 00:00:00 1970 +0000
+files:       f
+description:
+1
+
+
+
+hello<NUL><CR>
+some<LF>text<LF>
+rem empty<CR>
+
+[extensions]
+win32text = 
+[decode]
+** = macdecode:
+[encode]
+** = macencode:
+
+WARNING: f4.bat already has CR line endings
+and does not need EOL conversion by the win32text plugin.
+Before your next commit, please reconsider your encode/decode settings in 
+Mercurial.ini or ..../.hg/hgrc.
+3 files updated, 0 files merged, 0 files removed, 0 files unresolved
+hello<NUL><CR>
+some<CR>text<CR>
+rem empty<CR>
+
+# empty<CR>
+# empty<LF>
+% just linefeed<LF>
+% just linefeed<LF>
+no changes needed to linefeed
+% just linefeed<LF>
+M linefeed
+reverting linefeed
+% just linefeed<CR>