diff --git a/source/blender/io/stl/exporter/stl_export.cc b/source/blender/io/stl/exporter/stl_export.cc
index 82e5cba5be0..8bd023e72be 100644
--- a/source/blender/io/stl/exporter/stl_export.cc
+++ b/source/blender/io/stl/exporter/stl_export.cc
@@ -122,13 +122,17 @@ void export_frame(Depsgraph *depsgraph,
     mul_v3_m3v3(xform[3], axes_transform, obj_eval->object_to_world().location());
     xform[3][3] = obj_eval->object_to_world()[3][3];
 
+    const bool mirrored = is_negative_m4(xform);
+
     /* Write triangles. */
     const Span<float3> positions = mesh->vert_positions();
     const Span<int> corner_verts = mesh->corner_verts();
     for (const int3 &tri : mesh->corner_tris()) {
       PackedTriangle data{};
       for (int i = 0; i < 3; i++) {
-        float3 pos = positions[corner_verts[tri[i]]];
+        /* Reverse face order for mirrored objects. */
+        int idx = mirrored ? 2 - i : i;
+        float3 pos = positions[corner_verts[tri[idx]]];
         mul_m4_v3(xform, pos);
         pos *= global_scale;
         data.vertices[i] = pos;
diff --git a/tests/data b/tests/data
index 218087daf89..181a40d6c97 160000
--- a/tests/data
+++ b/tests/data
@@ -1 +1 @@
-Subproject commit 218087daf891d3eefd7ac2c66eb05f117f4510bd
+Subproject commit 181a40d6c972c591996c49588d18d6154b9fbc6a