diff --git a/lib/grit/git-ruby/internal/pack.rb b/lib/grit/git-ruby/internal/pack.rb
index d46ddcf4..f03a3030 100644
--- a/lib/grit/git-ruby/internal/pack.rb
+++ b/lib/grit/git-ruby/internal/pack.rb
@@ -13,8 +13,7 @@
 require 'grit/git-ruby/internal/raw_object'
 require 'grit/git-ruby/internal/file_window'
 
-PACK_SIGNATURE = "PACK"
-PACK_IDX_SIGNATURE = "\377tOc"
+PACK_IDX_SIGNATURE = [0xFF, 0x74, 0x4F, 0x63]
 
 module Grit
   module GitRuby
@@ -57,7 +56,7 @@ def with_idx(index_file = nil)
           end
 
           # read header
-          sig = idxfile.read(4)
+          sig = idxfile.read(4).unpack("C*")
           ver = idxfile.read(4).unpack("N")[0]
 
           if sig == PACK_IDX_SIGNATURE
diff --git a/lib/grit/ruby1.9.rb b/lib/grit/ruby1.9.rb
index 1ef4ade1..68c2e17e 100644
--- a/lib/grit/ruby1.9.rb
+++ b/lib/grit/ruby1.9.rb
@@ -1,4 +1,4 @@
-if ((defined? RUBY_VERSION) && (RUBY_VERSION[0..2] == "1.9"))
+if ((defined? RUBY_VERSION) && (['1.9', '2.0'].include? RUBY_VERSION[0..2]))
   class String
     def getord(offset); self[offset].ord; end
     def default_encoding!; force_encoding(Encoding.default_internal || Encoding::UTF_8); end