diff --git a/code/IOStreamBuffer.h b/code/IOStreamBuffer.h
index 5b00ef5d6..e82207340 100644
--- a/code/IOStreamBuffer.h
+++ b/code/IOStreamBuffer.h
@@ -47,15 +47,43 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 namespace Assimp {
 
+// ---------------------------------------------------------------------------
+/**
+ *  Implementation of a cached stream buffer.
+ */
 template<class T>
 class IOStreamBuffer {
 public:
+    /// @brief  The class constructor.
     IOStreamBuffer( size_t cache = 4096 * 4096 );
+
+    /// @brief  The class destructor.
     ~IOStreamBuffer();
+
+    /// @brief  Will open the cached access for a given stream.
+    /// @param  stream      The stream to cache.
+    /// @return true if successful.
     bool open( IOStream *stream );
+
+    /// @brief  Will close the cached access.
+    /// @return true if successful.
     bool close();
+
+    /// @brief  Returns the filesize.
+    /// @return The filesize.
     size_t size() const;
+    
+    /// @brief  Returns the cache size.
+    /// @return The cache size.
+    size_t cacheSize() const;
+
+    /// @brief  Will read the next block.
+    /// @return true if successful.
     bool readNextBlock();
+
+    /// @brief  Will read the next line.
+    /// @param  buffer      The buffer for the next line.
+    /// @return true if successful.
     bool getNextLine( std::vector<T> &buffer );
 
 private:
@@ -69,14 +97,14 @@ private:
 
 template<class T>
 inline
-IOStreamBuffer<T>::IOStreamBuffer( size_t cache = 4096 * 4096 )
-    : m_stream( nullptr )
-    , m_filesize( 0 )
-    , m_cacheSize( cache )
-    , m_cachePos( 0 )
-    , m_filePos( 0 ) {
+IOStreamBuffer<T>::IOStreamBuffer( size_t cache )
+: m_stream( nullptr )
+, m_filesize( 0 )
+, m_cacheSize( cache )
+, m_cachePos( 0 )
+, m_filePos( 0 ) {
     m_cache.resize( cache );
-    std::fill( m_cache.begin(), m_cache.end(), '\0' );
+    std::fill( m_cache.begin(), m_cache.end(), '\n' );
 }
 
 template<class T>
@@ -88,6 +116,10 @@ IOStreamBuffer<T>::~IOStreamBuffer() {
 template<class T>
 inline
 bool IOStreamBuffer<T>::open( IOStream *stream ) {
+    if ( nullptr != m_stream ) {
+        return false;
+    }
+
     if ( nullptr == stream ) {
         return false;
     }
@@ -123,6 +155,12 @@ size_t IOStreamBuffer<T>::size() const {
     return m_filesize;
 }
 
+template<class T>
+inline
+size_t IOStreamBuffer<T>::cacheSize() const {
+    return m_cacheSize;
+}
+
 template<class T>
 inline
 bool IOStreamBuffer<T>::readNextBlock() {
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 7c14dff0e..c23ad806f 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -70,6 +70,7 @@ SET( TEST_SRCS
   unit/utImporter.cpp
   unit/utImproveCacheLocality.cpp
   unit/utIOSystem.cpp
+  unit/utIOStreamBuffer.cpp
   unit/utIssues.cpp
   unit/utJoinVertices.cpp
   unit/utLimitBoneWeights.cpp
diff --git a/test/unit/TestIOStream.h b/test/unit/TestIOStream.h
new file mode 100644
index 000000000..1014a77d0
--- /dev/null
+++ b/test/unit/TestIOStream.h
@@ -0,0 +1,23 @@
+#pragma once
+
+#include "DefaultIOStream.h"
+
+using namespace ::Assimp;
+
+class TestDefaultIOStream : public DefaultIOStream {
+public:
+    TestDefaultIOStream()
+        : DefaultIOStream() {
+        // empty
+    }
+
+    TestDefaultIOStream( FILE* pFile, const std::string &strFilename )
+        : DefaultIOStream( pFile, strFilename ) {
+        // empty
+    }
+
+    virtual ~TestDefaultIOStream() {
+        // empty
+    }
+};
+
diff --git a/test/unit/utDefaultIOStream.cpp b/test/unit/utDefaultIOStream.cpp
index 7d3c07f20..50a15437c 100644
--- a/test/unit/utDefaultIOStream.cpp
+++ b/test/unit/utDefaultIOStream.cpp
@@ -37,7 +37,7 @@ THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 -------------------------------------------------------------------------*/
 #include <gtest/gtest.h>
-#include "DefaultIOStream.h"
+#include "TestIOStream.h"
 
 using namespace ::Assimp;
 
@@ -45,23 +45,6 @@ class utDefaultIOStream : public ::testing::Test {
     // empty
 };
 
-class TestDefaultIOStream : public DefaultIOStream {
-public:
-    TestDefaultIOStream()
-    : DefaultIOStream() {
-        // empty
-    }
-
-    TestDefaultIOStream( FILE* pFile, const std::string &strFilename )
-    : DefaultIOStream( pFile, strFilename ) {
-        // empty
-    }
-
-    virtual ~TestDefaultIOStream() {
-        // empty
-    }
-};
-
 TEST_F( utDefaultIOStream, FileSizeTest ) {
     char buffer[ L_tmpnam ];
     tmpnam( buffer );
diff --git a/test/unit/utIOStreamBuffer.cpp b/test/unit/utIOStreamBuffer.cpp
index 9d8d6ad96..ec70f759b 100644
--- a/test/unit/utIOStreamBuffer.cpp
+++ b/test/unit/utIOStreamBuffer.cpp
@@ -41,6 +41,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include "UnitTestPCH.h"
 #include "IOStreamBuffer.h"
+#include "TestIOStream.h"
 
 class IOStreamBufferTest : public ::testing::Test {
     // empty
@@ -58,6 +59,33 @@ TEST_F( IOStreamBufferTest, creationTest ) {
     EXPECT_TRUE( ok );
 }
 
+TEST_F( IOStreamBufferTest, accessCacheSizeTest ) {
+    IOStreamBuffer<char> myBuffer1;
+    EXPECT_NE( 0, myBuffer1.cacheSize() );
+
+    IOStreamBuffer<char> myBuffer2( 100 );
+    EXPECT_EQ( 100, myBuffer2.cacheSize() );
+}
+
+TEST_F( IOStreamBufferTest, open_close_Test ) {
+    IOStreamBuffer<char> myBuffer;
+
+    EXPECT_FALSE( myBuffer.open( nullptr ) );
+    EXPECT_FALSE( myBuffer.close() );
+
+    char buffer[ L_tmpnam ];
+    tmpnam( buffer );
+    std::FILE *fs( std::fopen( buffer, "w+" ) );
+    size_t written( std::fwrite( buffer, 1, sizeof( char ) * L_tmpnam, fs ) );
+    std::fflush( fs );
+
+    TestDefaultIOStream myStream( fs, buffer );
+
+    EXPECT_TRUE( myBuffer.open( &myStream ) );
+    EXPECT_FALSE( myBuffer.open( &myStream ) );
+    EXPECT_TRUE( myBuffer.close() );
+}
+
 TEST_F( IOStreamBufferTest, readlineTest ) {
 
 }
\ No newline at end of file