diff --git a/xs/src/libslic3r/IO.cpp b/xs/src/libslic3r/IO.cpp
index 7433d5465..0a0500a92 100644
--- a/xs/src/libslic3r/IO.cpp
+++ b/xs/src/libslic3r/IO.cpp
@@ -156,6 +156,9 @@ bool
 OBJ::write(const Model& model, std::string output_file)
 {
     TriangleMesh mesh = model.mesh();
+    // pre-emptively repair because object write can break 
+    // output
+    mesh.repair();
     return OBJ::write(mesh, output_file);
 }