diff --git a/code/AssetLib/3MF/D3MFImporter.cpp b/code/AssetLib/3MF/D3MFImporter.cpp
index e8529064c..9a5081db9 100644
--- a/code/AssetLib/3MF/D3MFImporter.cpp
+++ b/code/AssetLib/3MF/D3MFImporter.cpp
@@ -81,12 +81,17 @@ static constexpr aiImporterDesc desc = {
     "3mf"
 };
 
-bool D3MFImporter::CanRead(const std::string &filename, IOSystem *pIOHandler, bool /*checkSig*/) const {
+bool D3MFImporter::CanRead(const std::string &filename, IOSystem *pIOHandler, bool ) const {
     if (!ZipArchiveIOSystem::isZipArchive(pIOHandler, filename)) {
         return false;
     }
-    D3MF::D3MFOpcPackage opcPackage(pIOHandler, filename);
-    return opcPackage.validate();
+    static const char *const ModelRef = "3D/3dmodel.model";
+    ZipArchiveIOSystem archive(pIOHandler, filename);
+    if (!archive.Exists(ModelRef)) {
+        return false;
+    }
+
+    return true;
 }
 
 void D3MFImporter::SetupProperties(const Importer*) {
diff --git a/code/AssetLib/Irr/IRRLoader.cpp b/code/AssetLib/Irr/IRRLoader.cpp
index 99e053892..2a481a6d8 100644
--- a/code/AssetLib/Irr/IRRLoader.cpp
+++ b/code/AssetLib/Irr/IRRLoader.cpp
@@ -1234,7 +1234,10 @@ void IRRImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
     // Parse the XML
     // Find the scene root from document root.
     const pugi::xml_node &sceneRoot = documentRoot.child("irr_scene");
-    if (!sceneRoot) throw new DeadlyImportError("IRR: <irr_scene> not found in file");
+    if (!sceneRoot) {
+        delete root;
+        throw new DeadlyImportError("IRR: <irr_scene> not found in file");
+    }
     for (pugi::xml_node &child : sceneRoot.children()) {
         // XML elements are either nodes, animators, attributes, or materials
         if (!ASSIMP_stricmp(child.name(), "node")) {
diff --git a/code/AssetLib/MDL/MDLMaterialLoader.cpp b/code/AssetLib/MDL/MDLMaterialLoader.cpp
index 3d39fa645..f8dafdb3e 100644
--- a/code/AssetLib/MDL/MDLMaterialLoader.cpp
+++ b/code/AssetLib/MDL/MDLMaterialLoader.cpp
@@ -123,9 +123,8 @@ aiColor4D MDLImporter::ReplaceTextureWithColor(const aiTexture *pcTexture) {
 // Read a texture from a MDL3 file
 void MDLImporter::CreateTextureARGB8_3DGS_MDL3(const unsigned char *szData) {
     const MDL::Header *pcHeader = (const MDL::Header *)mBuffer; //the endianness is already corrected in the InternReadFile_3DGS_MDL345 function
-
-    VALIDATE_FILE_SIZE(szData + pcHeader->skinwidth *
-                                        pcHeader->skinheight);
+    const size_t len = pcHeader->skinwidth * pcHeader->skinheight;
+    VALIDATE_FILE_SIZE(szData + len);
 
     // allocate a new texture object
     aiTexture *pcNew = new aiTexture();
diff --git a/code/AssetLib/Q3BSP/Q3BSPFileImporter.cpp b/code/AssetLib/Q3BSP/Q3BSPFileImporter.cpp
index 3c56775e8..a82f29cf1 100644
--- a/code/AssetLib/Q3BSP/Q3BSPFileImporter.cpp
+++ b/code/AssetLib/Q3BSP/Q3BSPFileImporter.cpp
@@ -395,7 +395,10 @@ void Q3BSPFileImporter::createTriangleTopology(const Q3BSP::Q3BSPModel *pModel,
                 m_pCurrentFace->mIndices = new unsigned int[3];
                 m_pCurrentFace->mIndices[idx] = vertIdx;
             }
-        }
+		} else {
+			m_pCurrentFace->mIndices[idx] = vertIdx;
+		}
+
 
         pMesh->mVertices[vertIdx].Set(pVertex->vPosition.x, pVertex->vPosition.y, pVertex->vPosition.z);
         pMesh->mNormals[vertIdx].Set(pVertex->vNormal.x, pVertex->vNormal.y, pVertex->vNormal.z);
diff --git a/code/Common/DefaultIOSystem.cpp b/code/Common/DefaultIOSystem.cpp
index b28910c70..a72627154 100644
--- a/code/Common/DefaultIOSystem.cpp
+++ b/code/Common/DefaultIOSystem.cpp
@@ -99,12 +99,12 @@ bool DefaultIOSystem::Exists(const char *pFile) const {
         return false;
     }
 #else
-    FILE *file = ::fopen(pFile, "rb");
-    if (!file) {
+	struct stat statbuf;
+    stat(pFile, &statbuf);
+    // test for a regular file
+    if (!S_ISREG(statbuf.st_mode)) {
         return false;
     }
-
-    ::fclose(file);
 #endif
 
     return true;
@@ -116,6 +116,7 @@ IOStream *DefaultIOSystem::Open(const char *strFile, const char *strMode) {
     ai_assert(strFile != nullptr);
     ai_assert(strMode != nullptr);
     FILE *file;
+	
 #ifdef _WIN32
     std::wstring name = Utf8ToWide(strFile);
     if (name.empty()) {
@@ -126,6 +127,7 @@ IOStream *DefaultIOSystem::Open(const char *strFile, const char *strMode) {
 #else
     file = ::fopen(strFile, strMode);
 #endif
+	
     if (!file) {
         return nullptr;
     }