diff --git a/lib/zip/file.rb b/lib/zip/file.rb
index c0a44207..b5b85eea 100644
--- a/lib/zip/file.rb
+++ b/lib/zip/file.rb
@@ -134,12 +134,10 @@ def open_buffer(io, options = {})
           raise "Zip::File.open_buffer expects a String or IO-like argument (responds to #{IO_METHODS.join(', ')}). Found: #{io.class}"
         end
 
-        if io.is_a?(::String)
-          io = ::StringIO.new(io)
-        elsif io.respond_to?(:binmode)
-          # https://github.com/rubyzip/rubyzip/issues/119
-          io.binmode
-        end
+        io = ::StringIO.new(io) if io.is_a?(::String)
+
+        # https://github.com/rubyzip/rubyzip/issues/119
+        io.binmode if io.respond_to?(:binmode)
 
         zf = ::Zip::File.new(io, true, true, options)
         return zf unless block_given?
diff --git a/test/file_test.rb b/test/file_test.rb
index 53124bea..8bbf7cf8 100644
--- a/test/file_test.rb
+++ b/test/file_test.rb
@@ -97,6 +97,13 @@ def test_get_output_stream
     end
   end
 
+  def test_open_buffer_with_string
+    string = File.read('test/data/rubycode.zip')
+    ::Zip::File.open_buffer string do |zf|
+      assert zf.entries.map { |e| e.name }.include?('zippedruby1.rb')
+    end
+  end
+
   def test_open_buffer_with_stringio
     string_io = StringIO.new File.read('test/data/rubycode.zip')
     ::Zip::File.open_buffer string_io do |zf|