--- header-orig.py	2011-06-02 16:59:56.937459791 +0200
+++ header.py	2011-06-02 17:06:47.604116656 +0200
@@ -313,16 +313,17 @@
         formatter = _ValueFormatter(self._headerlen, maxlinelen,
                                     self._continuation_ws, splitchars)
         for string, charset in self._chunks:
-            lines = string.splitlines()
-            formatter.feed(lines[0], charset)
-            for line in lines[1:]:
-                formatter.newline()
-                if charset.header_encoding is not None:
-                    formatter.feed(self._continuation_ws, USASCII)
-                    line = ' ' + line.lstrip()
-                formatter.feed(line, charset)
-            if len(lines) > 1:
-                formatter.newline()
+            if string:
+                lines = string.splitlines()
+                formatter.feed(lines[0], charset)
+                for line in lines[1:]:
+                    formatter.newline()
+                    if charset.header_encoding is not None:
+                        formatter.feed(self._continuation_ws, USASCII)
+                        line = ' ' + line.lstrip()
+                    formatter.feed(line, charset)
+                if len(lines) > 1:
+                    formatter.newline()
             formatter.add_transition()
         value = formatter._str(linesep)
         if _embeded_header.search(value):