diff --git a/samples/app/MeshAssimp.cpp b/samples/app/MeshAssimp.cpp
index af4e8c9401..78b9b17d9a 100644
--- a/samples/app/MeshAssimp.cpp
+++ b/samples/app/MeshAssimp.cpp
@@ -648,8 +648,6 @@ bool MeshAssimp::setFromFile(Asset& asset, std::map<std::string, MaterialInstanc
             // we only support triangles
             aiProcess_Triangulate);
 
-    scene = importer.ApplyPostProcessing(aiProcess_CalcTangentSpace);
-
     size_t index = importer.GetImporterIndex(asset.file.getExtension().c_str());
     const aiImporterDesc* importerDesc = importer.GetImporterInfo(index);
     bool isGLTF = importerDesc &&
@@ -842,12 +840,8 @@ void MeshAssimp::processNode(Asset& asset,
                             bitangent = normalize(cross(normal, float3{1.0, 0.0, 0.0}));
                             tangent = normalize(cross(normal, bitangent));
                         } else {
-                            // In assimp, the CalcTangentsProcess algorithm generates tangents in
-                            // the +U direction and bitangents in the +V direction, but the glTF
-                            // conformance suite (see NormalTangentTest) reveals that bitangents
-                            // should be flipped.
                             tangent = tangents[j];
-                            bitangent = -bitangents[j];
+                            bitangent = bitangents[j];
                         }
 
                         quatf q = filament::math::details::TMat33<float>::packTangentFrame({tangent, bitangent, normal});
diff --git a/third_party/libassimp/code/CalcTangentsProcess.cpp b/third_party/libassimp/code/CalcTangentsProcess.cpp
index 54e55fc5a7..a25fbb27c8 100644
--- a/third_party/libassimp/code/CalcTangentsProcess.cpp
+++ b/third_party/libassimp/code/CalcTangentsProcess.cpp
@@ -196,14 +196,14 @@ bool CalcTangentsProcess::ProcessMesh( aiMesh* pMesh, unsigned int meshIndex)
         }
 
         // tangent points in the direction where to positive X axis of the texture coord's would point in model space
-        // bitangent's points along the positive Y axis of the texture coord's, respectively
+        // bitangent's points along the negative Y axis of the texture coord's, respectively
         aiVector3D tangent, bitangent;
         tangent.x = (w.x * sy - v.x * ty) * dirCorrection;
         tangent.y = (w.y * sy - v.y * ty) * dirCorrection;
         tangent.z = (w.z * sy - v.z * ty) * dirCorrection;
-        bitangent.x = (w.x * sx - v.x * tx) * dirCorrection;
-        bitangent.y = (w.y * sx - v.y * tx) * dirCorrection;
-        bitangent.z = (w.z * sx - v.z * tx) * dirCorrection;
+        bitangent.x = (v.x * tx - w.x * sx) * dirCorrection;
+        bitangent.y = (v.y * tx - w.y * sx) * dirCorrection;
+        bitangent.z = (v.z * tx - w.z * sx) * dirCorrection;
 
         // store for every vertex of that face
         for( unsigned int b = 0; b < face.mNumIndices; ++b ) {
diff --git a/third_party/libassimp/tnt/README.md b/third_party/libassimp/tnt/README.md
index 9eae75e58c..e14adb70e4 100644
--- a/third_party/libassimp/tnt/README.md
+++ b/third_party/libassimp/tnt/README.md
@@ -29,3 +29,7 @@ In glTF2Importer.cpp, change from:
     ai_anim->mNumChannels = r.skins[0].jointNames.size();
 to:
     ai_anim->mNumChannels = r.skins.Size() > 0 ? r.skins[0].jointNames.size() : 0;
+
+(2)
+
+Negate the bitangent in CalcTangentsProcess.cpp