diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -399,9 +399,9 @@ def show_changeset(ui, repo, opts):
 
     if tmpl or mapfile:
         if mapfile:
-            if not os.path.isfile(mapfile):
-                mapname = templater.templatepath('map-cmdline.' + mapfile)
-                if not mapname: mapname = templater.templatepath(mapfile)
+            if not os.path.split(mapfile)[0]:
+                mapname = (templater.templatepath('map-cmdline.' + mapfile)
+                           or templater.templatepath(mapfile))
                 if mapname: mapfile = mapname
         try:
             t = templater.changeset_templater(ui, repo, mapfile)
diff --git a/tests/test-command-template b/tests/test-command-template
--- a/tests/test-command-template
+++ b/tests/test-command-template
@@ -65,6 +65,10 @@ echo '[ui]' > .hg/hgrc
 echo 'style = t' >> .hg/hgrc
 hg log
 
+echo '# issue338'
+hg log --style=changelog > changelog
+cat changelog
+
 echo "# keys work"
 for key in author branches date desc file_adds file_dels files \
         manifest node parents rev tags; do
diff --git a/tests/test-command-template.out b/tests/test-command-template.out
--- a/tests/test-command-template.out
+++ b/tests/test-command-template.out
@@ -76,6 +76,33 @@ 3
 2
 1
 0
+# issue338
+1970-01-16  person  <person>
+
+	* c:
+	no user, no domain
+	[10e46f2dcbf4] [tip]
+
+1970-01-14  other  <other@place>
+
+	* c:
+	no person
+	[97054abb4ab8]
+
+1970-01-13  A. N. Other  <other@place>
+
+	* b:
+	other 1 other 2
+
+	other 3
+	[b608e9d1a3f0]
+
+1970-01-12  User Name  <user@hostname>
+
+	* a:
+	line 1 line 2
+	[1e4e1b8f71e0]
+
 # keys work
 author: person
 author: other@place