Index: lib/rexml/formatters/pretty.rb
===================================================================
--- lib/rexml/formatters/pretty.rb	(revision 18162)
+++ lib/rexml/formatters/pretty.rb	(working copy)
@@ -127,7 +127,7 @@
       def wrap(string, width)
         # Recursively wrap string at width.
         return string if string.length <= width
-        place = string.rindex(' ', width) # Position in string with last ' ' before cutoff
+        place = string.rindex(' ', width) || width # Position in string with last ' ' before cutoff
         return string[0,place] + "\n" + wrap(string[place+1..-1], width)
       end