diff --git a/app/models/optimized_image.rb b/app/models/optimized_image.rb
index 0bb3ebbfa..9f4149d2a 100644
--- a/app/models/optimized_image.rb
+++ b/app/models/optimized_image.rb
@@ -16,8 +16,8 @@ class OptimizedImage < ActiveRecord::Base
       image_info = FastImage.new(temp_path)
       thumbnail = OptimizedImage.new({
         upload_id: upload.id,
-        sha: Digest::SHA1.file(temp_path).hexdigest,
-        ext: File.extname(temp_path),
+        sha1: Digest::SHA1.file(temp_path).hexdigest,
+        extension: File.extname(temp_path),
         width: image_info.size[0],
         height: image_info.size[1]
       })
@@ -49,11 +49,11 @@ class OptimizedImage < ActiveRecord::Base
   end
 
   def optimized_path
-    "uploads/#{RailsMultisite::ConnectionManagement.current_db}/_optimized/#{sha[0..2]}/#{sha[3..5]}"
+    "uploads/#{RailsMultisite::ConnectionManagement.current_db}/_optimized/#{sha1[0..2]}/#{sha1[3..5]}"
   end
 
   def filename
-    "#{sha[6..16]}_#{width}x#{height}#{ext}"
+    "#{sha1[6..16]}_#{width}x#{height}#{extension}"
   end
 
 end
@@ -63,8 +63,8 @@ end
 # Table name: optimized_images
 #
 #  id        :integer          not null, primary key
-#  sha       :string(255)      not null
-#  ext       :string(255)      not null
+#  sha1      :string(40)       not null
+#  extension :string(10)       not null
 #  width     :integer          not null
 #  height    :integer          not null
 #  upload_id :integer          not null
diff --git a/db/migrate/20130617014127_rename_sha_and_ext_columns.rb b/db/migrate/20130617014127_rename_sha_and_ext_columns.rb
new file mode 100644
index 000000000..d0077df77
--- /dev/null
+++ b/db/migrate/20130617014127_rename_sha_and_ext_columns.rb
@@ -0,0 +1,15 @@
+class RenameShaAndExtColumns < ActiveRecord::Migration
+  def up
+    rename_column :optimized_images, :sha, :sha1
+    change_column :optimized_images, :sha1, :string, limit: 40
+    rename_column :optimized_images, :ext, :extension
+    change_column :optimized_images, :extension, :string, limit: 10
+  end
+
+  def down
+    change_column :optimized_images, :extension, :string, limit: 255
+    rename_column :optimized_images, :extension, :ext
+    change_column :optimized_images, :sha1, :string, limit: 255
+    rename_column :optimized_images, :sha1, :sha
+  end
+end
diff --git a/spec/models/optimized_image_spec.rb b/spec/models/optimized_image_spec.rb
index aa85e11be..bed715a7c 100644
--- a/spec/models/optimized_image_spec.rb
+++ b/spec/models/optimized_image_spec.rb
@@ -20,8 +20,8 @@ describe OptimizedImage do
     it "works" do
       Tempfile.any_instance.expects(:close).once
       Tempfile.any_instance.expects(:unlink).once
-      oi.sha.should == "da39a3ee5e6b4b0d3255bfef95601890afd80709"
-      oi.ext.should == ".jpg"
+      oi.sha1.should == "da39a3ee5e6b4b0d3255bfef95601890afd80709"
+      oi.extension.should == ".jpg"
       oi.width.should == 244
       oi.height.should == 66
     end