diff --git a/code/GenFaceNormalsProcess.cpp b/code/GenFaceNormalsProcess.cpp
index 2639868f1..43960ac3b 100644
--- a/code/GenFaceNormalsProcess.cpp
+++ b/code/GenFaceNormalsProcess.cpp
@@ -73,6 +73,7 @@ GenFaceNormalsProcess::~GenFaceNormalsProcess()
 // ------------------------------------------------------------------------------------------------
 // Returns whether the processing step is present in the given flag field.
 bool GenFaceNormalsProcess::IsActive( unsigned int pFlags) const {
+    force_ = (pFlags & aiProcess_ForceGenNormals) != 0;
     return  (pFlags & aiProcess_GenNormals) != 0;
 }
 
@@ -105,7 +106,8 @@ void GenFaceNormalsProcess::Execute( aiScene* pScene) {
 bool GenFaceNormalsProcess::GenMeshFaceNormals (aiMesh* pMesh)
 {
     if (NULL != pMesh->mNormals) {
-        return false;
+        if (force_) delete[] pMesh->mNormals;
+        else return false;
     }
 
     // If the mesh consists of lines and/or points but not of
@@ -134,7 +136,7 @@ bool GenFaceNormalsProcess::GenMeshFaceNormals (aiMesh* pMesh)
         const aiVector3D* pV1 = &pMesh->mVertices[face.mIndices[0]];
         const aiVector3D* pV2 = &pMesh->mVertices[face.mIndices[1]];
         const aiVector3D* pV3 = &pMesh->mVertices[face.mIndices[face.mNumIndices-1]];
-        const aiVector3D vNor = ((*pV2 - *pV1) ^ (*pV3 - *pV1)).Normalize();
+        const aiVector3D vNor = ((*pV2 - *pV1) ^ (*pV3 - *pV1)).NormalizeSafe();
 
         for (unsigned int i = 0;i < face.mNumIndices;++i) {
             pMesh->mNormals[face.mIndices[i]] = vNor;
diff --git a/code/GenFaceNormalsProcess.h b/code/GenFaceNormalsProcess.h
index 27ae7acac..e2f41e07f 100644
--- a/code/GenFaceNormalsProcess.h
+++ b/code/GenFaceNormalsProcess.h
@@ -78,7 +78,8 @@ public:
 
 
 private:
-    bool GenMeshFaceNormals (aiMesh* pcMesh);
+    bool GenMeshFaceNormals(aiMesh* pcMesh);
+    mutable bool force_ = false;
 };
 
 } // end of namespace Assimp
diff --git a/code/GenVertexNormalsProcess.cpp b/code/GenVertexNormalsProcess.cpp
index f0fb0ba19..1778ef513 100644
--- a/code/GenVertexNormalsProcess.cpp
+++ b/code/GenVertexNormalsProcess.cpp
@@ -72,6 +72,7 @@ GenVertexNormalsProcess::~GenVertexNormalsProcess() {
 // Returns whether the processing step is present in the given flag field.
 bool GenVertexNormalsProcess::IsActive( unsigned int pFlags) const
 {
+    force_ = (pFlags & aiProcess_ForceGenNormals) != 0;
     return (pFlags & aiProcess_GenSmoothNormals) != 0;
 }
 
@@ -113,8 +114,10 @@ void GenVertexNormalsProcess::Execute( aiScene* pScene)
 // Executes the post processing step on the given imported data.
 bool GenVertexNormalsProcess::GenMeshVertexNormals (aiMesh* pMesh, unsigned int meshIndex)
 {
-    if (NULL != pMesh->mNormals)
-        return false;
+    if (NULL != pMesh->mNormals) {
+        if (force_) delete[] pMesh->mNormals;
+        else return false;
+    }
 
     // If the mesh consists of lines and/or points but not of
     // triangles or higher-order polygons the normal vectors
diff --git a/code/GenVertexNormalsProcess.h b/code/GenVertexNormalsProcess.h
index 5ab9eb6f5..2efafa302 100644
--- a/code/GenVertexNormalsProcess.h
+++ b/code/GenVertexNormalsProcess.h
@@ -107,6 +107,7 @@ private:
 
     /** Configuration option: maximum smoothing angle, in radians*/
     ai_real configMaxAngle;
+    mutable bool force_ = false;
 };
 
 } // end of namespace Assimp
diff --git a/include/assimp/postprocess.h b/include/assimp/postprocess.h
index f6c0833ee..1cb9c72f8 100644
--- a/include/assimp/postprocess.h
+++ b/include/assimp/postprocess.h
@@ -555,10 +555,13 @@ enum aiPostProcessSteps
      *  of the imported model. And if so, it uses that.
      */
     aiProcess_EmbedTextures  = 0x10000000,
-
+        
     // aiProcess_GenEntityMeshes = 0x100000,
     // aiProcess_OptimizeAnimations = 0x200000
     // aiProcess_FixTexturePaths = 0x200000
+
+
+    aiProcess_ForceGenNormals = 0x20000000,
 };