diff --git a/code/AssetLib/HMP/HMPFileData.h b/code/AssetLib/HMP/HMPFileData.h
index 4fc54e2c8..5f6ca4f55 100644
--- a/code/AssetLib/HMP/HMPFileData.h
+++ b/code/AssetLib/HMP/HMPFileData.h
@@ -49,7 +49,7 @@ namespace HMP   {
 #include <assimp/Compiler/pushpack1.h>
 #include <stdint.h>
 
-// to make it easier for us, we test the magic word against both "endianesses"
+// to make it easier for us, we test the magic word against both "endiannesses"
 #define AI_HMP_MAGIC_NUMBER_BE_4    AI_MAKE_MAGIC("HMP4")
 #define AI_HMP_MAGIC_NUMBER_LE_4    AI_MAKE_MAGIC("4PMH")
 
diff --git a/code/AssetLib/MD2/MD2FileData.h b/code/AssetLib/MD2/MD2FileData.h
index 6c1f7069b..0dba71e56 100644
--- a/code/AssetLib/MD2/MD2FileData.h
+++ b/code/AssetLib/MD2/MD2FileData.h
@@ -55,7 +55,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 namespace Assimp    {
 namespace MD2   {
 
-// to make it easier for us, we test the magic word against both "endianesses"
+// to make it easier for us, we test the magic word against both "endiannesses"
 #define AI_MD2_MAGIC_NUMBER_BE  AI_MAKE_MAGIC("IDP2")
 #define AI_MD2_MAGIC_NUMBER_LE  AI_MAKE_MAGIC("2PDI")
 
diff --git a/code/AssetLib/MD3/MD3FileData.h b/code/AssetLib/MD3/MD3FileData.h
index 4251243b3..86d2647b6 100644
--- a/code/AssetLib/MD3/MD3FileData.h
+++ b/code/AssetLib/MD3/MD3FileData.h
@@ -62,7 +62,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 namespace Assimp {
 namespace MD3   {
 
-// to make it easier for us, we test the magic word against both "endianesses"
+// to make it easier for us, we test the magic word against both "endiannesses"
 #define AI_MD3_MAGIC_NUMBER_BE  AI_MAKE_MAGIC("IDP3")
 #define AI_MD3_MAGIC_NUMBER_LE  AI_MAKE_MAGIC("3PDI")
 
diff --git a/code/AssetLib/MDC/MDCFileData.h b/code/AssetLib/MDC/MDCFileData.h
index 5d7084b5d..4c5b4127c 100644
--- a/code/AssetLib/MDC/MDCFileData.h
+++ b/code/AssetLib/MDC/MDCFileData.h
@@ -61,7 +61,7 @@ http://themdcfile.planetwolfenstein.gamespy.com/MDC_File_Format.pdf
 namespace Assimp {
 namespace MDC {
 
-// to make it easier for us, we test the magic word against both "endianesses"
+// to make it easier for us, we test the magic word against both "endiannesses"
 #define AI_MDC_MAGIC_NUMBER_BE  AI_MAKE_MAGIC("CPDI")
 #define AI_MDC_MAGIC_NUMBER_LE  AI_MAKE_MAGIC("IDPC")
 
diff --git a/code/AssetLib/MDL/MDLFileData.h b/code/AssetLib/MDL/MDLFileData.h
index 62117e788..2aff59856 100644
--- a/code/AssetLib/MDL/MDLFileData.h
+++ b/code/AssetLib/MDL/MDLFileData.h
@@ -67,7 +67,7 @@ namespace Assimp    {
 namespace MDL   {
 
 // -------------------------------------------------------------------------------------
-// to make it easier for us, we test the magic word against both "endianesses"
+// to make it easier for us, we test the magic word against both "endiannesses"
 
 // magic bytes used in Quake 1 MDL meshes
 #define AI_MDL_MAGIC_NUMBER_BE  AI_MAKE_MAGIC("IDPO")
diff --git a/code/AssetLib/Obj/ObjExporter.cpp b/code/AssetLib/Obj/ObjExporter.cpp
index a5d8325fc..7c5c051f3 100644
--- a/code/AssetLib/Obj/ObjExporter.cpp
+++ b/code/AssetLib/Obj/ObjExporter.cpp
@@ -59,9 +59,9 @@ namespace Assimp {
 
 // ------------------------------------------------------------------------------------------------
 // Worker function for exporting a scene to Wavefront OBJ. Prototyped and registered in Exporter.cpp
-void ExportSceneObj(const char* pFile,IOSystem* pIOSystem, const aiScene* pScene, const ExportProperties* /*pProperties*/) {
+void ExportSceneObj(const char* pFile,IOSystem* pIOSystem, const aiScene* pScene, const ExportProperties* props) {
     // invoke the exporter
-    ObjExporter exporter(pFile, pScene);
+    ObjExporter exporter(pFile, pScene, false, props);
 
     if (exporter.mOutput.fail() || exporter.mOutputMat.fail()) {
         throw DeadlyExportError("output data creation failed. Most likely the file became too large: " + std::string(pFile));
@@ -86,9 +86,9 @@ void ExportSceneObj(const char* pFile,IOSystem* pIOSystem, const aiScene* pScene
 
 // ------------------------------------------------------------------------------------------------
 // Worker function for exporting a scene to Wavefront OBJ without the material file. Prototyped and registered in Exporter.cpp
-void ExportSceneObjNoMtl(const char* pFile,IOSystem* pIOSystem, const aiScene* pScene, const ExportProperties* ) {
+void ExportSceneObjNoMtl(const char* pFile,IOSystem* pIOSystem, const aiScene* pScene, const ExportProperties* props) {
     // invoke the exporter
-    ObjExporter exporter(pFile, pScene, true);
+    ObjExporter exporter(pFile, pScene, true, props);
 
     if (exporter.mOutput.fail() || exporter.mOutputMat.fail()) {
         throw DeadlyExportError("output data creation failed. Most likely the file became too large: " + std::string(pFile));
@@ -111,7 +111,7 @@ void ExportSceneObjNoMtl(const char* pFile,IOSystem* pIOSystem, const aiScene* p
 static const std::string MaterialExt = ".mtl";
 
 // ------------------------------------------------------------------------------------------------
-ObjExporter::ObjExporter(const char* _filename, const aiScene* pScene, bool noMtl)
+ObjExporter::ObjExporter(const char* _filename, const aiScene* pScene, bool noMtl, const ExportProperties* props)
 : filename(_filename)
 , pScene(pScene)
 , vn()
@@ -130,7 +130,10 @@ ObjExporter::ObjExporter(const char* _filename, const aiScene* pScene, bool noMt
     mOutputMat.imbue(l);
     mOutputMat.precision(ASSIMP_AI_REAL_TEXT_PRECISION);
 
-    WriteGeometryFile(noMtl);
+    WriteGeometryFile(
+        noMtl,
+        props == nullptr ? true : props->GetPropertyBool("bJoinIdenticalVertices", true)
+    );
     if ( !noMtl ) {
         WriteMaterialFile();
     }
@@ -255,14 +258,14 @@ void ObjExporter::WriteMaterialFile() {
     }
 }
 
-void ObjExporter::WriteGeometryFile(bool noMtl) {
+void ObjExporter::WriteGeometryFile(bool noMtl, bool merge_identical_vertices) {
     WriteHeader(mOutput);
     if (!noMtl)
         mOutput << "mtllib "  << GetMaterialLibName() << endl << endl;
 
     // collect mesh geometry
     aiMatrix4x4 mBase;
-    AddNode(pScene->mRootNode, mBase);
+    AddNode(pScene->mRootNode, mBase, merge_identical_vertices);
 
     // write vertex positions with colors, if any
     mVpMap.getKeys( vp );
@@ -330,7 +333,7 @@ void ObjExporter::WriteGeometryFile(bool noMtl) {
 }
 
 // ------------------------------------------------------------------------------------------------
-void ObjExporter::AddMesh(const aiString& name, const aiMesh* m, const aiMatrix4x4& mat) {
+void ObjExporter::AddMesh(const aiString& name, const aiMesh* m, const aiMatrix4x4& mat, bool merge_identical_vertices) {
     mMeshes.emplace_back();
     MeshInstance& mesh = mMeshes.back();
 
@@ -362,13 +365,14 @@ void ObjExporter::AddMesh(const aiString& name, const aiMesh* m, const aiMatrix4
         for(unsigned int a = 0; a < f.mNumIndices; ++a) {
             const unsigned int idx = f.mIndices[a];
 
+            const unsigned int fi = merge_identical_vertices ? 0 : idx;
             aiVector3D vert = mat * m->mVertices[idx];
 
             if ( nullptr != m->mColors[ 0 ] ) {
                 aiColor4D col4 = m->mColors[ 0 ][ idx ];
-                face.indices[a].vp = mVpMap.getIndex({vert, aiColor3D(col4.r, col4.g, col4.b)});
+                face.indices[a].vp = mVpMap.getIndex({vert, aiColor3D(col4.r, col4.g, col4.b), fi});
             } else {
-                face.indices[a].vp = mVpMap.getIndex({vert, aiColor3D(0,0,0)});
+                face.indices[a].vp = mVpMap.getIndex({vert, aiColor3D(0,0,0), fi});
             }
 
             if (m->mNormals) {
@@ -388,21 +392,21 @@ void ObjExporter::AddMesh(const aiString& name, const aiMesh* m, const aiMatrix4
 }
 
 // ------------------------------------------------------------------------------------------------
-void ObjExporter::AddNode(const aiNode* nd, const aiMatrix4x4& mParent) {
+void ObjExporter::AddNode(const aiNode* nd, const aiMatrix4x4& mParent, bool merge_identical_vertices) {
     const aiMatrix4x4& mAbs = mParent * nd->mTransformation;
 
     aiMesh *cm( nullptr );
     for(unsigned int i = 0; i < nd->mNumMeshes; ++i) {
         cm = pScene->mMeshes[nd->mMeshes[i]];
         if (nullptr != cm) {
-            AddMesh(cm->mName, pScene->mMeshes[nd->mMeshes[i]], mAbs);
+            AddMesh(cm->mName, pScene->mMeshes[nd->mMeshes[i]], mAbs, merge_identical_vertices);
         } else {
-            AddMesh(nd->mName, pScene->mMeshes[nd->mMeshes[i]], mAbs);
+            AddMesh(nd->mName, pScene->mMeshes[nd->mMeshes[i]], mAbs, merge_identical_vertices);
         }
     }
 
     for(unsigned int i = 0; i < nd->mNumChildren; ++i) {
-        AddNode(nd->mChildren[i], mAbs);
+        AddNode(nd->mChildren[i], mAbs, merge_identical_vertices);
     }
 }
 
diff --git a/code/AssetLib/Obj/ObjExporter.h b/code/AssetLib/Obj/ObjExporter.h
index a64f38f74..4c92aa16f 100644
--- a/code/AssetLib/Obj/ObjExporter.h
+++ b/code/AssetLib/Obj/ObjExporter.h
@@ -51,6 +51,8 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <vector>
 #include <map>
 
+#include <assimp/Exporter.hpp>
+
 struct aiScene;
 struct aiNode;
 struct aiMesh;
@@ -63,7 +65,7 @@ namespace Assimp {
 class ObjExporter {
 public:
     /// Constructor for a specific scene to export
-    ObjExporter(const char* filename, const aiScene* pScene, bool noMtl=false);
+    ObjExporter(const char* filename, const aiScene* pScene, bool noMtl=false, const ExportProperties* props = nullptr);
     ~ObjExporter();
     std::string GetMaterialLibName();
     std::string GetMaterialLibFileName();
@@ -97,10 +99,10 @@ private:
 
     void WriteHeader(std::ostringstream& out);
     void WriteMaterialFile();
-    void WriteGeometryFile(bool noMtl=false);
+    void WriteGeometryFile(bool noMtl=false, bool merge_identical_vertices = false);
     std::string GetMaterialName(unsigned int index);
-    void AddMesh(const aiString& name, const aiMesh* m, const aiMatrix4x4& mat);
-    void AddNode(const aiNode* nd, const aiMatrix4x4& mParent);
+    void AddMesh(const aiString& name, const aiMesh* m, const aiMatrix4x4& mat, bool merge_identical_vertices);
+    void AddNode(const aiNode* nd, const aiMatrix4x4& mParent, bool merge_identical_vertices);
 
 private:
     std::string filename;
@@ -109,6 +111,7 @@ private:
     struct vertexData {
         aiVector3D vp;
         aiColor3D vc; // OBJ does not support 4D color
+        uint32_t index = 0;
     };
 
     std::vector<aiVector3D> vn, vt;
@@ -133,7 +136,7 @@ private:
             if (a.vc.g > b.vc.g) return false;
             if (a.vc.b < b.vc.b) return true;
             if (a.vc.b > b.vc.b) return false;
-            return false;
+            return a.index < b.index;
         }
     };
 
diff --git a/doc/dox.h b/doc/dox.h
index 1d5f59aa4..2fb127a2b 100644
--- a/doc/dox.h
+++ b/doc/dox.h
@@ -1545,7 +1545,7 @@ Don't trust the input data! Check all offsets!
 Mixed stuff for internal use by loaders, mostly documented (most of them are already included by <i>AssimpPCH.h</i>):
 <ul>
 <li><b>ByteSwapper</b> (<i>ByteSwapper.h</i>) - manual byte swapping stuff for binary loaders.</li>
-<li><b>StreamReader</b> (<i>StreamReader.h</i>) - safe, endianess-correct, binary reading.</li>
+<li><b>StreamReader</b> (<i>StreamReader.h</i>) - safe, endianness-correct, binary reading.</li>
 <li><b>IrrXML</b> (<i>irrXMLWrapper.h</i>)  - for XML-parsing (SAX.</li>
 <li><b>CommentRemover</b> (<i>RemoveComments.h</i>) - remove single-line and multi-line comments from a text file.</li>
 <li>fast_atof, strtoul10, strtoul16, SkipSpaceAndLineEnd, SkipToNextToken .. large family of low-level
diff --git a/include/assimp/ByteSwapper.h b/include/assimp/ByteSwapper.h
index 179f7b555..f738ae701 100644
--- a/include/assimp/ByteSwapper.h
+++ b/include/assimp/ByteSwapper.h
@@ -263,7 +263,7 @@ struct ByteSwapper<T,false> {
 };
 
 // --------------------------------------------------------------------------------------------
-template <bool SwapEndianess, typename T, bool RuntimeSwitch>
+template <bool SwapEndianness, typename T, bool RuntimeSwitch>
 struct Getter {
     void operator() (T* inout, bool le) {
 #ifdef AI_BUILD_BIG_ENDIAN
@@ -278,12 +278,12 @@ struct Getter {
     }
 };
 
-template <bool SwapEndianess, typename T>
-struct Getter<SwapEndianess,T,false> {
+template <bool SwapEndianness, typename T>
+struct Getter<SwapEndianness,T,false> {
 
     void operator() (T* inout, bool /*le*/) {
         // static branch
-        ByteSwapper<T,(SwapEndianess && sizeof(T)>1)> () (inout);
+        ByteSwapper<T,(SwapEndianness && sizeof(T)>1)> () (inout);
     }
 };
 } // end Intern
diff --git a/include/assimp/StreamReader.h b/include/assimp/StreamReader.h
index 66e83b7ac..cc74bd652 100644
--- a/include/assimp/StreamReader.h
+++ b/include/assimp/StreamReader.h
@@ -68,7 +68,7 @@ namespace Assimp {
  *
  *  XXX switch from unsigned int for size types to size_t? or ptrdiff_t?*/
 // --------------------------------------------------------------------------------------------
-template <bool SwapEndianess = false, bool RuntimeSwitch = false>
+template <bool SwapEndianness = false, bool RuntimeSwitch = false>
 class StreamReader {
 public:
     using diff = size_t;
@@ -84,7 +84,7 @@ public:
      *    reads from the current position to the end of the stream.
      *  @param le If @c RuntimeSwitch is true: specifies whether the
      *    stream is in little endian byte order. Otherwise the
-     *    endianness information is contained in the @c SwapEndianess
+     *    endianness information is contained in the @c SwapEndianness
      *    template parameter and this parameter is meaningless.  */
     StreamReader(std::shared_ptr<IOStream> stream, bool le = false) :
             mStream(stream),
@@ -291,7 +291,7 @@ public:
 
         T f;
         ::memcpy(&f, mCurrent, sizeof(T));
-        Intern::Getter<SwapEndianess, T, RuntimeSwitch>()(&f, mLe);
+        Intern::Getter<SwapEndianness, T, RuntimeSwitch>()(&f, mLe);
         mCurrent += sizeof(T);
 
         return f;
diff --git a/include/assimp/StreamWriter.h b/include/assimp/StreamWriter.h
index 7b84789d1..32da6911b 100644
--- a/include/assimp/StreamWriter.h
+++ b/include/assimp/StreamWriter.h
@@ -65,7 +65,7 @@ namespace Assimp {
  *  stream is to be determined at runtime.
  */
 // --------------------------------------------------------------------------------------------
-template <bool SwapEndianess = false, bool RuntimeSwitch = false>
+template <bool SwapEndianness = false, bool RuntimeSwitch = false>
 class StreamWriter {
     enum {
         INITIAL_CAPACITY = 1024
@@ -82,7 +82,7 @@ public:
           continues at the current position of the stream cursor.
      *  @param le If @c RuntimeSwitch is true: specifies whether the
      *    stream is in little endian byte order. Otherwise the
-     *    endianness information is defined by the @c SwapEndianess
+     *    endianness information is defined by the @c SwapEndianness
      *    template parameter and this parameter is meaningless.  */
     StreamWriter(std::shared_ptr<IOStream> stream, bool le = false)
         : stream(stream)
@@ -260,7 +260,7 @@ public:
     /** Generic write method. ByteSwap::Swap(T*) *must* be defined */
     template <typename T>
     void Put(T f)   {
-        Intern :: Getter<SwapEndianess,T,RuntimeSwitch>() (&f, le);
+        Intern :: Getter<SwapEndianness,T,RuntimeSwitch>() (&f, le);
 
         if (cursor + sizeof(T) >= buffer.size()) {
             buffer.resize(cursor + sizeof(T));
diff --git a/test/unit/UnitTestFileGenerator.h b/test/unit/UnitTestFileGenerator.h
index 2166c6939..93007bad9 100644
--- a/test/unit/UnitTestFileGenerator.h
+++ b/test/unit/UnitTestFileGenerator.h
@@ -44,9 +44,14 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <cstdlib>
 #include <gtest/gtest.h>
 
+#if defined(_MSC_VER) || defined(__MINGW64__) || defined(__MINGW32__)
+#define TMP_PATH "./"
+#elif defined(__GNUC__) || defined(__clang__)
+#define TMP_PATH "/tmp/"
+#endif
+
 #if defined(_MSC_VER)
 #include <io.h>
-#define TMP_PATH "./"
 inline FILE* MakeTmpFile(char* tmplate)
 {
     auto pathtemplate = _mktemp(tmplate);
@@ -60,7 +65,6 @@ inline FILE* MakeTmpFile(char* tmplate)
     return fs;
 }
 #elif defined(__GNUC__) || defined(__clang__)
-#define TMP_PATH "/tmp/"
 inline FILE* MakeTmpFile(char* tmplate)
 {
     auto fd = mkstemp(tmplate);