diff --git a/Library/Homebrew/cmd/bottle.rb b/Library/Homebrew/cmd/bottle.rb
index 8d52296531..a06545d42f 100644
--- a/Library/Homebrew/cmd/bottle.rb
+++ b/Library/Homebrew/cmd/bottle.rb
@@ -131,8 +131,8 @@ module Homebrew
       ohai "Determining #{f.name} bottle revision..."
       versions = FormulaVersions.new(f)
       bottle_revisions = versions.bottle_version_map("origin/master")[f.pkg_version]
-      bottle_revisions.pop if bottle_revisions.last > 0
-      bottle_revision = bottle_revisions.any? ? bottle_revisions.max + 1 : 0
+      bottle_revisions.pop if bottle_revisions.last.to_i > 0
+      bottle_revision = bottle_revisions.any? ? bottle_revisions.max.to_i + 1 : 0
     end
 
     filename = Bottle::Filename.create(f, bottle_tag, bottle_revision)