diff --git a/lib/paperclip/io_adapters/attachment_adapter.rb b/lib/paperclip/io_adapters/attachment_adapter.rb
index 69ee55c3c..7719af474 100644
--- a/lib/paperclip/io_adapters/attachment_adapter.rb
+++ b/lib/paperclip/io_adapters/attachment_adapter.rb
@@ -49,6 +49,7 @@ def cache_current_values
 
     def copy_to_tempfile(src)
       dest = Tempfile.new(src.original_filename)
+      dest.binmode
       FileUtils.cp(src.path(:original), dest.path)
       dest
     end
diff --git a/lib/paperclip/io_adapters/file_adapter.rb b/lib/paperclip/io_adapters/file_adapter.rb
index a4c523c6a..515b6ff86 100644
--- a/lib/paperclip/io_adapters/file_adapter.rb
+++ b/lib/paperclip/io_adapters/file_adapter.rb
@@ -57,6 +57,7 @@ def path
 
     def copy_to_tempfile(src)
       dest = Tempfile.new(original_filename)
+      dest.binmode
       FileUtils.cp(src.path, dest.path)
       dest
     end
diff --git a/lib/paperclip/io_adapters/uploaded_file_adapter.rb b/lib/paperclip/io_adapters/uploaded_file_adapter.rb
index ef0828f5f..36f8777cc 100644
--- a/lib/paperclip/io_adapters/uploaded_file_adapter.rb
+++ b/lib/paperclip/io_adapters/uploaded_file_adapter.rb
@@ -51,6 +51,7 @@ def path
 
     def copy_to_tempfile(src)
       dest = Tempfile.new(original_filename)
+      dest.binmode
       FileUtils.cp(src.path, dest.path)
       dest
     end
diff --git a/test/attachment_adapter_test.rb b/test/attachment_adapter_test.rb
index 87e44cb6d..d4cda57be 100644
--- a/test/attachment_adapter_test.rb
+++ b/test/attachment_adapter_test.rb
@@ -5,6 +5,8 @@ def setup
     rebuild_model :path => "tmp/:class/:attachment/:style/:filename"
     @attachment = Dummy.new.avatar
     @file = File.new(fixture_file("5k.png"))
+    @file.binmode
+
     @attachment.assign(@file)
     @attachment.save
     @subject = Paperclip.io_adapters.for(@attachment)
@@ -14,6 +16,10 @@ def setup
     assert_equal "5k.png", @subject.original_filename
   end
 
+  should "force binmode on tempfile" do
+    assert @subject.instance_variable_get("@tempfile").binmode?
+  end
+
   should "get the content type" do
     assert_equal "image/png", @subject.content_type
   end
diff --git a/test/file_adapter_test.rb b/test/file_adapter_test.rb
index f9e1ee22b..61c9a455e 100644
--- a/test/file_adapter_test.rb
+++ b/test/file_adapter_test.rb
@@ -4,6 +4,7 @@ class FileAdapterTest < Test::Unit::TestCase
   context "a new instance" do
     setup do
       @file = File.new(fixture_file("5k.png"))
+      @file.binmode
       @subject = Paperclip.io_adapters.for(@file)
     end
 
@@ -11,6 +12,10 @@ class FileAdapterTest < Test::Unit::TestCase
       assert_equal "5k.png", @subject.original_filename
     end
 
+    should "force binmode on tempfile" do
+      assert @subject.instance_variable_get("@tempfile").binmode?
+    end
+
     should "get the content type" do
       assert_equal "image/png", @subject.content_type
     end
diff --git a/test/uploaded_file_adapter_test.rb b/test/uploaded_file_adapter_test.rb
index c27c7846e..0d120f433 100644
--- a/test/uploaded_file_adapter_test.rb
+++ b/test/uploaded_file_adapter_test.rb
@@ -5,11 +5,14 @@ class UploadedFileAdapterTest < Test::Unit::TestCase
     context "with UploadedFile responding to #tempfile" do
       setup do
         class UploadedFile < OpenStruct; end
+        tempfile = File.new(fixture_file("5k.png"))
+        tempfile.binmode
+
         @file = UploadedFile.new(
           :original_filename => "5k.png",
           :content_type => "image/png",
           :head => "",
-          :tempfile => File.new(fixture_file("5k.png"))
+          :tempfile => tempfile
         )
         @subject = Paperclip.io_adapters.for(@file)
       end
@@ -18,6 +21,10 @@ class UploadedFile < OpenStruct; end
         assert_equal "5k.png", @subject.original_filename
       end
 
+      should "force binmode on tempfile" do
+        assert @subject.instance_variable_get("@tempfile").binmode?
+      end
+
       should "get the content type" do
         assert_equal "image/png", @subject.content_type
       end
@@ -58,6 +65,10 @@ class UploadedFile < OpenStruct; end
         assert_equal "5k.png", @subject.original_filename
       end
 
+      should "force binmode on tempfile" do
+        assert @subject.instance_variable_get("@tempfile").binmode?
+      end
+
       should "get the content type" do
         assert_equal "image/png", @subject.content_type
       end
@@ -76,7 +87,9 @@ class UploadedFile < OpenStruct; end
       end
 
       should "read the contents of the file" do
-        expected = File.new(@file.path).read
+        expected_file = File.new(@file.path)
+        expected_file.binmode
+        expected = expected_file.read
         assert expected.length > 0
         assert_equal expected, @subject.read
       end