diff --git a/include/yaml-cpp/ostream_wrapper.h b/include/yaml-cpp/ostream_wrapper.h
index e37f9a6..cc2ef56 100644
--- a/include/yaml-cpp/ostream_wrapper.h
+++ b/include/yaml-cpp/ostream_wrapper.h
@@ -41,7 +41,7 @@ class ostream_wrapper {
 
  private:
   mutable std::vector<char> m_buffer;
-  std::ostream* m_pStream;
+  std::ostream* const m_pStream;
 
   std::size_t m_pos;
   std::size_t m_row, m_col;
diff --git a/test/ostream_wrapper_test.cpp b/test/ostream_wrapper_test.cpp
index 4fbb4df..d325a51 100644
--- a/test/ostream_wrapper_test.cpp
+++ b/test/ostream_wrapper_test.cpp
@@ -1,15 +1,66 @@
 #include "yaml-cpp/ostream_wrapper.h"
 
+#include <sstream>
+
 #include "gtest/gtest.h"
 
 namespace {
-class OstreamWrapperTest : public ::testing::Test {
- protected:
-};
-
-// Tests that the Foo::Bar() method does Abc.
-TEST_F(OstreamWrapperTest, ConstructNoWrite) {
+TEST(OstreamWrapperTest, BufferNoWrite) {
   YAML::ostream_wrapper wrapper;
   EXPECT_STREQ("", wrapper.str());
 }
+
+TEST(OstreamWrapperTest, BufferWriteStr) {
+  YAML::ostream_wrapper wrapper;
+  wrapper.write(std::string("Hello, world"));
+  EXPECT_STREQ("Hello, world", wrapper.str());
+}
+
+TEST(OstreamWrapperTest, BufferWriteCStr) {
+  YAML::ostream_wrapper wrapper;
+  wrapper.write("Hello, world");
+  EXPECT_STREQ("Hello, world", wrapper.str());
+}
+
+TEST(OstreamWrapperTest, StreamNoWrite) {
+  std::stringstream stream;
+  YAML::ostream_wrapper wrapper(stream);
+  EXPECT_STREQ(NULL, wrapper.str());
+  EXPECT_EQ("", stream.str());
+}
+
+TEST(OstreamWrapperTest, StreamWriteStr) {
+  std::stringstream stream;
+  YAML::ostream_wrapper wrapper(stream);
+  wrapper.write(std::string("Hello, world"));
+  EXPECT_STREQ(NULL, wrapper.str());
+  EXPECT_EQ("Hello, world", stream.str());
+}
+
+TEST(OstreamWrapperTest, StreamWriteCStr) {
+  std::stringstream stream;
+  YAML::ostream_wrapper wrapper(stream);
+  wrapper.write("Hello, world");
+  EXPECT_STREQ(NULL, wrapper.str());
+  EXPECT_EQ("Hello, world", stream.str());
+}
+
+TEST(OstreamWrapperTest, Position) {
+  YAML::ostream_wrapper wrapper;
+  wrapper.write("Hello, world\n");
+  EXPECT_EQ(1, wrapper.row());
+  EXPECT_EQ(0, wrapper.col());
+  EXPECT_EQ(13, wrapper.pos());
+}
+
+TEST(OstreamWrapperTest, Comment) {
+  YAML::ostream_wrapper wrapper;
+  wrapper.write("Hello, world ");
+  wrapper.set_comment();
+  EXPECT_TRUE(wrapper.comment());
+  wrapper.write("foo");
+  EXPECT_TRUE(wrapper.comment());
+  wrapper.write("\n");
+  EXPECT_FALSE(wrapper.comment());
+}
 }