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/src/ostream_wrapper.cpp b/src/ostream_wrapper.cpp
index 558bd7b..bf9aa6e 100644
--- a/src/ostream_wrapper.cpp
+++ b/src/ostream_wrapper.cpp
@@ -4,7 +4,7 @@
 
 namespace YAML {
 ostream_wrapper::ostream_wrapper()
-    : m_buffer(1),
+    : m_buffer(1, '\0'),
       m_pStream(0),
       m_pos(0),
       m_row(0),
@@ -24,8 +24,9 @@ void ostream_wrapper::write(const std::string& str) {
     std::copy(str.begin(), str.end(), &m_buffer[m_pos]);
   }
 
-  for (std::size_t i = 0; i < str.size(); i++)
+  for (std::size_t i = 0; i < str.size(); i++) {
     update_pos(str[i]);
+  }
 }
 
 void ostream_wrapper::write(const char* str, std::size_t size) {
@@ -36,8 +37,9 @@ void ostream_wrapper::write(const char* str, std::size_t size) {
     std::copy(str, str + size, &m_buffer[m_pos]);
   }
 
-  for (std::size_t i = 0; i < size; i++)
+  for (std::size_t i = 0; i < size; i++) {
     update_pos(str[i]);
+  }
 }
 
 void ostream_wrapper::update_pos(char ch) {
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 403b1df..1f2df7c 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -1,8 +1,8 @@
 add_subdirectory(gtest-1.7.0)
 include_directories(gtest-1.7.0/include)
 
-file(GLOB test_headers [a-z]*.h)
-file(GLOB test_sources [a-z]*.cpp)
+file(GLOB test_headers [a-z_]*.h)
+file(GLOB test_sources [a-z_]*.cpp)
 file(GLOB test_new_api_sources new-api/[a-z]*.cpp)
 
 list(APPEND test_sources ${test_new_api_sources})
diff --git a/test/ostream_wrapper_test.cpp b/test/ostream_wrapper_test.cpp
new file mode 100644
index 0000000..d325a51
--- /dev/null
+++ b/test/ostream_wrapper_test.cpp
@@ -0,0 +1,66 @@
+#include "yaml-cpp/ostream_wrapper.h"
+
+#include <sstream>
+
+#include "gtest/gtest.h"
+
+namespace {
+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());
+}
+}