diff --git a/code/CInterfaceIOWrapper.cpp b/code/CInterfaceIOWrapper.cpp
new file mode 100644
index 000000000..0a80c1990
--- /dev/null
+++ b/code/CInterfaceIOWrapper.cpp
@@ -0,0 +1,134 @@
+/*
+---------------------------------------------------------------------------
+Open Asset Import Library (assimp)
+---------------------------------------------------------------------------
+
+Copyright (c) 2006-2016, assimp team
+
+All rights reserved.
+
+Redistribution and use of this software in source and binary forms,
+with or without modification, are permitted provided that the following
+conditions are met:
+
+* Redistributions of source code must retain the above
+  copyright notice, this list of conditions and the
+  following disclaimer.
+
+* Redistributions in binary form must reproduce the above
+  copyright notice, this list of conditions and the
+  following disclaimer in the documentation and/or other
+  materials provided with the distribution.
+
+* Neither the name of the assimp team, nor the names of its
+  contributors may be used to endorse or promote products
+  derived from this software without specific prior
+  written permission of the assimp team.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+---------------------------------------------------------------------------
+*/
+
+/** @file aiFileIO -> IOSystem wrapper*/
+
+#include "CInterfaceIOWrapper.h"
+
+namespace Assimp    {
+
+CIOStreamWrapper::~CIOStreamWrapper(void)
+{
+    /* Various places depend on this destructor to close the file */
+    if (mFile) {
+        mIO->mFileSystem->CloseProc(mIO->mFileSystem, mFile);
+        mFile = nullptr;
+    }
+}
+
+// ...................................................................
+size_t CIOStreamWrapper::Read(void* pvBuffer,
+    size_t pSize,
+    size_t pCount
+){
+    // need to typecast here as C has no void*
+    return mFile->ReadProc(mFile,(char*)pvBuffer,pSize,pCount);
+}
+
+// ...................................................................
+size_t CIOStreamWrapper::Write(const void* pvBuffer,
+    size_t pSize,
+    size_t pCount
+){
+    // need to typecast here as C has no void*
+    return mFile->WriteProc(mFile,(const char*)pvBuffer,pSize,pCount);
+}
+
+// ...................................................................
+aiReturn CIOStreamWrapper::Seek(size_t pOffset,
+    aiOrigin pOrigin
+){
+    return mFile->SeekProc(mFile,pOffset,pOrigin);
+}
+
+// ...................................................................
+size_t CIOStreamWrapper::Tell(void) const {
+    return mFile->TellProc(mFile);
+}
+
+// ...................................................................
+size_t CIOStreamWrapper::FileSize() const {
+    return mFile->FileSizeProc(mFile);
+}
+
+// ...................................................................
+void CIOStreamWrapper::Flush () {
+    return mFile->FlushProc(mFile);
+}
+
+// ------------------------------------------------------------------------------------------------
+// Custom IOStream implementation for the C-API
+bool CIOSystemWrapper::Exists( const char* pFile) const {
+    aiFile* p = mFileSystem->OpenProc(mFileSystem,pFile,"rb");
+    if (p){
+        mFileSystem->CloseProc(mFileSystem,p);
+        return true;
+    }
+    return false;
+}
+
+// ...................................................................
+char CIOSystemWrapper::getOsSeparator() const {
+#ifndef _WIN32
+    return '/';
+#else
+    return '\\';
+#endif
+}
+
+// ...................................................................
+IOStream* CIOSystemWrapper::Open(const char* pFile,const char* pMode) {
+    aiFile* p = mFileSystem->OpenProc(mFileSystem,pFile,pMode);
+    if (!p) {
+        return NULL;
+    }
+    return new CIOStreamWrapper(p, this);
+}
+
+// ...................................................................
+void CIOSystemWrapper::Close( IOStream* pFile) {
+    if (!pFile) {
+        return;
+    }
+    delete pFile;
+}
+
+}
diff --git a/code/CInterfaceIOWrapper.h b/code/CInterfaceIOWrapper.h
index beffd8678..0172fb49f 100644
--- a/code/CInterfaceIOWrapper.h
+++ b/code/CInterfaceIOWrapper.h
@@ -50,106 +50,43 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 namespace Assimp    {
 
+class CIOSystemWrapper;
+
 // ------------------------------------------------------------------------------------------------
 // Custom IOStream implementation for the C-API
 class CIOStreamWrapper : public IOStream
 {
-    friend class CIOSystemWrapper;
 public:
-
-    explicit CIOStreamWrapper(aiFile* pFile)
-        : mFile(pFile)
+    explicit CIOStreamWrapper(aiFile* pFile, CIOSystemWrapper* io)
+        : mFile(pFile),
+        mIO(io)
     {}
+    ~CIOStreamWrapper(void);
 
-    // ...................................................................
-    size_t Read(void* pvBuffer,
-        size_t pSize,
-        size_t pCount
-    ){
-        // need to typecast here as C has no void*
-        return mFile->ReadProc(mFile,(char*)pvBuffer,pSize,pCount);
-    }
-
-    // ...................................................................
-    size_t Write(const void* pvBuffer,
-        size_t pSize,
-        size_t pCount
-    ){
-        // need to typecast here as C has no void*
-        return mFile->WriteProc(mFile,(const char*)pvBuffer,pSize,pCount);
-    }
-
-    // ...................................................................
-    aiReturn Seek(size_t pOffset,
-        aiOrigin pOrigin
-    ){
-        return mFile->SeekProc(mFile,pOffset,pOrigin);
-    }
-
-    // ...................................................................
-    size_t Tell(void) const {
-        return mFile->TellProc(mFile);
-    }
-
-    // ...................................................................
-    size_t  FileSize() const {
-        return mFile->FileSizeProc(mFile);
-    }
-
-    // ...................................................................
-    void Flush () {
-        return mFile->FlushProc(mFile);
-    }
+    size_t Read(void* pvBuffer, size_t pSize, size_t pCount);
+    size_t Write(const void* pvBuffer, size_t pSize, size_t pCount);
+    aiReturn Seek(size_t pOffset, aiOrigin pOrigin);
+    size_t Tell(void) const;
+    size_t FileSize() const;
+    void Flush();
 
 private:
     aiFile* mFile;
+    CIOSystemWrapper* mIO;
 };
 
-// ------------------------------------------------------------------------------------------------
-// Custom IOStream implementation for the C-API
 class CIOSystemWrapper : public IOSystem
 {
+    friend class CIOStreamWrapper;
 public:
     explicit CIOSystemWrapper(aiFileIO* pFile)
         : mFileSystem(pFile)
     {}
 
-    // ...................................................................
-    bool Exists( const char* pFile) const {
-        aiFile* p = mFileSystem->OpenProc(mFileSystem,pFile,"rb");
-        if (p){
-            mFileSystem->CloseProc(mFileSystem,p);
-            return true;
-        }
-        return false;
-    }
-
-    // ...................................................................
-    char getOsSeparator() const {
-#ifndef _WIN32
-        return '/';
-#else
-        return '\\';
-#endif
-    }
-
-    // ...................................................................
-    IOStream* Open(const char* pFile,const char* pMode = "rb") {
-        aiFile* p = mFileSystem->OpenProc(mFileSystem,pFile,pMode);
-        if (!p) {
-            return NULL;
-        }
-        return new CIOStreamWrapper(p);
-    }
-
-    // ...................................................................
-    void Close( IOStream* pFile) {
-        if (!pFile) {
-            return;
-        }
-        mFileSystem->CloseProc(mFileSystem,((CIOStreamWrapper*) pFile)->mFile);
-        delete pFile;
-    }
+    bool Exists( const char* pFile) const;
+    char getOsSeparator() const;
+    IOStream* Open(const char* pFile,const char* pMode = "rb");
+    void Close( IOStream* pFile);
 private:
     aiFileIO* mFileSystem;
 };
diff --git a/code/CMakeLists.txt b/code/CMakeLists.txt
index 10979df5c..771b9e24c 100644
--- a/code/CMakeLists.txt
+++ b/code/CMakeLists.txt
@@ -128,6 +128,7 @@ SET( Common_SRCS
   DefaultIOStream.h
   DefaultIOSystem.cpp
   DefaultIOSystem.h
+  CInterfaceIOWrapper.cpp
   CInterfaceIOWrapper.h
   Hash.h
   Importer.cpp