diff --git a/mercurial/minirst.py b/mercurial/minirst.py
--- a/mercurial/minirst.py
+++ b/mercurial/minirst.py
@@ -113,7 +113,7 @@ def findliteralblocks(blocks):
 
 _bulletre = re.compile(r'(-|[0-9A-Za-z]+\.|\(?[0-9A-Za-z]+\)) ')
 _optionre = re.compile(r'^(--[a-z-]+)((?:[ =][a-zA-Z][\w-]*)?  +)(.*)$')
-_fieldre = re.compile(r':(?![: ])([^:]*)(?<! ):( +)(.*)')
+_fieldre = re.compile(r':(?![: ])([^:]*)(?<! ):[ ]+(.*)')
 _definitionre = re.compile(r'[^ ]')
 
 def splitparagraphs(blocks):
@@ -159,6 +159,33 @@ def splitparagraphs(blocks):
     return blocks
 
 
+_fieldwidth = 12
+
+def updatefieldlists(blocks):
+    """Find key and maximum key width for field lists."""
+    i = 0
+    while i < len(blocks):
+        if blocks[i]['type'] != 'field':
+            i += 1
+            continue
+
+        keywidth = 0
+        j = i
+        while j < len(blocks) and blocks[j]['type'] == 'field':
+            m = _fieldre.match(blocks[j]['lines'][0])
+            key, rest = m.groups()
+            blocks[j]['lines'][0] = rest
+            blocks[j]['key'] = key
+            keywidth = max(keywidth, len(key))
+            j += 1
+
+        for block in blocks[i:j]:
+            block['keywidth'] = keywidth
+        i = j + 1
+
+    return blocks
+
+
 def findsections(blocks):
     """Finds sections.
 
@@ -228,11 +255,21 @@ def formatblock(block, width):
         m = _bulletre.match(block['lines'][0])
         subindent = indent + m.end() * ' '
     elif block['type'] == 'field':
-        m = _fieldre.match(block['lines'][0])
-        key, spaces, rest = m.groups()
-        # Turn ":foo: bar" into "foo   bar".
-        block['lines'][0] = '%s  %s%s' % (key, spaces, rest)
-        subindent = indent + (2 + len(key) + len(spaces)) * ' '
+        keywidth = block['keywidth']
+        key = block['key']
+
+        subindent = indent + _fieldwidth * ' '
+        if len(key) + 2 > _fieldwidth:
+            # key too large, use full line width
+            key = key.ljust(width)
+        elif keywidth + 2 < _fieldwidth:
+            # all keys are small, add only two spaces
+            key = key.ljust(keywidth + 2)
+            subindent = indent + (keywidth + 2) * ' '
+        else:
+            # mixed sizes, use fieldwidth for this one
+            key = key.ljust(_fieldwidth)
+        block['lines'][0] = key + block['lines'][0]
     elif block['type'] == 'option':
         m = _optionre.match(block['lines'][0])
         option, arg, rest = m.groups()
@@ -252,6 +289,7 @@ def format(text, width, indent=0):
     blocks = findliteralblocks(blocks)
     blocks = inlineliterals(blocks)
     blocks = splitparagraphs(blocks)
+    blocks = updatefieldlists(blocks)
     blocks = findsections(blocks)
     blocks = addmargins(blocks)
     return '\n'.join(formatblock(b, width) for b in blocks)
@@ -272,6 +310,7 @@ if __name__ == "__main__":
     blocks = debug(findliteralblocks, blocks)
     blocks = debug(inlineliterals, blocks)
     blocks = debug(splitparagraphs, blocks)
+    blocks = debug(updatefieldlists, blocks)
     blocks = debug(findsections, blocks)
     blocks = debug(addmargins, blocks)
     print '\n'.join(formatblock(b, 30) for b in blocks)
diff --git a/tests/test-dispatch.out b/tests/test-dispatch.out
--- a/tests/test-dispatch.out
+++ b/tests/test-dispatch.out
@@ -13,9 +13,9 @@ output the current or given revision of 
     a format string. The formatting rules are the same as for the export
     command, with the following additions:
 
-    "%s"   basename of file being printed
-    "%d"   dirname of file being printed, or '.' if in repository root
-    "%p"   root-relative path name of file being printed
+    "%s"  basename of file being printed
+    "%d"  dirname of file being printed, or '.' if in repository root
+    "%p"  root-relative path name of file being printed
 
 options:
 
diff --git a/tests/test-minirst.py b/tests/test-minirst.py
--- a/tests/test-minirst.py
+++ b/tests/test-minirst.py
@@ -134,13 +134,14 @@ debugformat('options', options, 30)
 
 
 fields = """
-Field lists give a simple two-column layout:
+:a: First item.
+:ab: Second item. Indentation and wrapping
+     is handled automatically.
 
-:key:         The whitespace following the key is
-  significant for the wrapping of this text.
-:another key: More text.
-    The indentation on the following
-    lines is not significant.
+Next list:
+
+:small: The larger key below triggers full indentation here.
+:much too large: This key is big enough to get its own line.
 """
 
 debugformat('fields', fields, 60)
diff --git a/tests/test-minirst.py.out b/tests/test-minirst.py.out
--- a/tests/test-minirst.py.out
+++ b/tests/test-minirst.py.out
@@ -215,29 +215,34 @@ normal paragraph:
 
 fields formatted to fit within 60 characters:
 ----------------------------------------------------------------------
-Field lists give a simple two-column layout:
+a   First item.
+ab  Second item. Indentation and wrapping is handled
+    automatically.
 
-key           The whitespace following the key is
-              significant for the wrapping of this text.
-another key   More text. The indentation on the following
-              lines is not significant.
+Next list:
+
+small       The larger key below triggers full indentation
+            here.
+much too large
+            This key is big enough to get its own line.
 ----------------------------------------------------------------------
 
 fields formatted to fit within 30 characters:
 ----------------------------------------------------------------------
-Field lists give a simple two-
-column layout:
+a   First item.
+ab  Second item. Indentation
+    and wrapping is handled
+    automatically.
+
+Next list:
 
-key           The whitespace
-              following the
-              key is
-              significant for
-              the wrapping of
-              this text.
-another key   More text. The
-              indentation on
-              the following
-              lines is not
-              significant.
+small       The larger key
+            below triggers
+            full indentation
+            here.
+much too large
+            This key is big
+            enough to get its
+            own line.
 ----------------------------------------------------------------------