Index: test/DefaultFileSystem.cpp
===================================================================
--- a/test/DefaultFileSystem.cpp
+++ b/test/DefaultFileSystem.cpp
@@ -21,30 +21,28 @@
 
 namespace
 {
   const std::string testPath = "libadblockplus-t\xc3\xa4st-file";
 
   void WriteString(AdblockPlus::FileSystem& fileSystem,
                    const std::string& content)
   {
-    std::stringstream input;
-    input << content;
-    fileSystem.Write(testPath, input);
+    AdblockPlus::FileSystem::IOBuffer buffer(content.cbegin(), content.cend());
+    fileSystem.Write(testPath, buffer);
   }
 }
 
 TEST(DefaultFileSystemTest, WriteReadRemove)
 {
   AdblockPlus::DefaultFileSystem fileSystem;
   WriteString(fileSystem, "foo");
-  std::stringstream output;
-  output << fileSystem.Read(testPath)->rdbuf();
+  auto output = fileSystem.Read(testPath);
   fileSystem.Remove(testPath);
-  ASSERT_EQ("foo", output.str());
+  ASSERT_EQ("foo", std::string(output.cbegin(), output.cend()));
 }
 
 TEST(DefaultFileSystemTest, StatWorkingDirectory)
 {
   AdblockPlus::DefaultFileSystem fileSystem;
   const AdblockPlus::FileSystem::StatResult result = fileSystem.Stat(".");
   ASSERT_TRUE(result.exists);
   ASSERT_TRUE(result.isDirectory);