diff --git a/mercurial/cmdutil.py b/mercurial/cmdutil.py
--- a/mercurial/cmdutil.py
+++ b/mercurial/cmdutil.py
@@ -898,7 +898,7 @@ def makefilename(ctx, pat,
         'R': lambda: '%d' % ctx.rev(),
         'h': lambda: short(ctx.node()),
         'm': lambda: re.sub('[^\w]', '_',
-                            ctx.description().rstrip().splitlines()[0]),
+                            ctx.description().strip().splitlines()[0]),
         'r': lambda: ('%d' % ctx.rev()).zfill(revwidth or 0),
         '%': lambda: '%',
         'b': lambda: os.path.basename(ctx.repo().root),
diff --git a/tests/test-export.t b/tests/test-export.t
--- a/tests/test-export.t
+++ b/tests/test-export.t
@@ -184,7 +184,7 @@ Checking if only alphanumeric characters
   $ hg commit -m " !\"#$%&(,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]"'^'"_\`abcdefghijklmnopqrstuvwxyz{|}~"
   $ hg export -v -o %m.patch tip
   exporting patch:
-  ____________0123456789_______ABCDEFGHIJKLMNOPQRSTUVWXYZ______abcdefghijklmnopqrstuvwxyz____.patch
+  ___________0123456789_______ABCDEFGHIJKLMNOPQRSTUVWXYZ______abcdefghijklmnopqrstuvwxyz____.patch
 
 Invalid pattern in file name: