diff --git a/Library/Homebrew/version.rb b/Library/Homebrew/version.rb
index 9669c2af3f..f7d194bace 100644
--- a/Library/Homebrew/version.rb
+++ b/Library/Homebrew/version.rb
@@ -90,7 +90,7 @@ class Version
   end
 
   def to_s
-    @version
+    @version.dup
   end
   alias_method :to_str, :to_s