diff --git a/lib/rubygems/text.rb b/lib/rubygems/text.rb
index 88d4ce59b4b9..3b86282b4845 100644
--- a/lib/rubygems/text.rb
+++ b/lib/rubygems/text.rb
@@ -28,9 +28,10 @@ def format_text(text, wrap, indent = 0)
     while work.length > wrap do
       if work =~ /^(.{0,#{wrap}})[ \n]/
         result << $1.rstrip
-        work.slice!(0, $&.length)
+        work = work.slice($&.length..-1)
       else
-        result << work.slice!(0, wrap)
+        result << work.slice(0, wrap)
+        work = work.slice(wrap..-1)
       end
     end