diff --git a/lib/gollum/git_access.rb b/lib/gollum/git_access.rb
index 9887f70c..a27225b4 100644
--- a/lib/gollum/git_access.rb
+++ b/lib/gollum/git_access.rb
@@ -39,7 +39,11 @@ module Gollum
     end
 
     def ref_to_sha(ref)
-      @ref_map[ref] ||= ref_to_sha!(ref)
+      if ref =~ /^[0-9a-f]{40}$/
+        ref
+      else
+        @ref_map[ref] ||= ref_to_sha!(ref)
+      end
     end
 
     def tree(ref)
diff --git a/test/test_git_access.rb b/test/test_git_access.rb
new file mode 100644
index 00000000..8d991fea
--- /dev/null
+++ b/test/test_git_access.rb
@@ -0,0 +1,31 @@
+require File.join(File.dirname(__FILE__), *%w[helper])
+
+context "GitAccess" do
+  setup do
+    @access = Gollum::GitAccess.new(testpath("examples/lotr.git"))
+  end
+
+  test "#tree_map_for caches ref and tree" do
+    assert @access.ref_map.empty?
+    assert @access.tree_map.empty?
+    @access.tree 'master'
+    assert_equal({"master"=>"60f12f4254f58801b9ee7db7bca5fa8aeefaa56b"}, @access.ref_map)
+  
+    map = @access.tree_map['60f12f4254f58801b9ee7db7bca5fa8aeefaa56b']
+    assert_equal 'Bilbo-Baggins.md',        map[0].path
+    assert_equal '',                        map[0].dir
+    assert_equal map[0].path,               map[0].name
+    assert_equal 'Mordor/Eye-Of-Sauron.md', map[3].path
+    assert_equal '/Mordor',                 map[3].dir
+    assert_equal 'Eye-Of-Sauron.md',        map[3].name
+  end
+
+  test "#tree_map_for only caches tree for commit" do
+    assert @access.tree_map.empty?
+    @access.tree '60f12f4254f58801b9ee7db7bca5fa8aeefaa56b'
+    assert @access.ref_map.empty?
+
+    entry = @access.tree_map['60f12f4254f58801b9ee7db7bca5fa8aeefaa56b'][0]
+    assert_equal 'Bilbo-Baggins.md', entry.path
+  end
+end
\ No newline at end of file
diff --git a/test/test_wiki.rb b/test/test_wiki.rb
index 36642161..7d9ac0b3 100644
--- a/test/test_wiki.rb
+++ b/test/test_wiki.rb
@@ -2,8 +2,7 @@ require File.join(File.dirname(__FILE__), *%w[helper])
 
 context "Wiki" do
   setup do
-    @access = Gollum::GitAccess.new(testpath("examples/lotr.git"))
-    @wiki   = Gollum::Wiki.new(@access)
+    @wiki = Gollum::Wiki.new(testpath("examples/lotr.git"))
   end
 
   test "repo path" do
@@ -60,30 +59,6 @@ context "Wiki" do
     assert_equal({:message => 'abc', :name => 'bob', :email => 'foo@bar.com'},
       @wiki.normalize_commit(commit.dup))
   end
-
-  #test "#tree_map_for caches ref and tree" do
-  #  assert @wiki.ref_map.empty?
-  #  assert @wiki.tree_map.empty?
-  #  @wiki.tree_map_for 'master'
-  #  assert_equal({"master"=>"60f12f4254f58801b9ee7db7bca5fa8aeefaa56b"}, @wiki.ref_map)
-  #
-  #  map = @wiki.tree_map['60f12f4254f58801b9ee7db7bca5fa8aeefaa56b']
-  #  assert_equal 'Bilbo-Baggins.md',        map[0].path
-  #  assert_equal '',                        map[0].dir
-  #  assert_equal map[0].path,               map[0].name
-  #  assert_equal 'Mordor/Eye-Of-Sauron.md', map[3].path
-  #  assert_equal '/Mordor',                 map[3].dir
-  #  assert_equal 'Eye-Of-Sauron.md',        map[3].name
-  #end
-  #
-  #test "#tree_map_for only caches tree for commit" do
-  #  assert @access.tree_map.empty?
-  #  @access.tree '60f12f4254f58801b9ee7db7bca5fa8aeefaa56b'
-  #  assert @access.ref_map.empty?
-  #
-  #  entry = @access.tree_map['60f12f4254f58801b9ee7db7bca5fa8aeefaa56b'][0]
-  #  assert_equal 'Bilbo-Baggins.md', entry.path
-  #end
 end
 
 context "Wiki page previewing" do